Use LocationLink in go to definition

[gabritto]

This PR makes go to definition and go to type definition use LocationLinks, which has roughly the same shape of what we return in Strada.
It also adds support for location link's origin selection range in the baseline tests. In Strada, we had to verify.baseline... methods for go to def, one which included the origin selection range (response body's textSpan), and one which did not, so now we do the same here.

The origin selection range also shows up in baselines, although in a buggy way: it only shows up if there are no definition locations in the same file. I believe this is a bug in Strada's fourslash, but I've preserved the behavior so it's easier to compare the baselines. Another oddity here is that Strada's fourslash does not use the contextSpan property of definitions in the baselines, even though baselines for e.g. rename do use context spans (they show up as <| ... |> in baselines).

I'll enable go to def baseline diffs in another PR, and this PR also helps reduce noise in the diffs.

Fixes #1439

[Copilot]

Pull Request Overview

Purpose: Switch go to definition and go to type definition to return LocationLinks (with originSelectionRange) and extend fourslash baseline infrastructure to capture (optionally) the origin selection range, mirroring Strada behavior — including its known quirk of only showing the origin selection range when no definition appears in the same file.
Key changes:

• LanguageService and LSP server updated to pass and honor client definition capabilities, producing LocationLinks when supported.
• Fourslash harness enhanced (new default definition capabilities, updated VerifyBaselineGoToDefinition signature, baseline generation logic, conversion script adjustments) to optionally include the origin selection range.
• Widespread baseline test updates to reflect new [| |] origin selection markers and modified API usage.

Reviewed Changes

Copilot reviewed 266 out of 266 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
testdata/baselines/reference/fourslash/goToDefinition/importTypeNodeGoToDefinition.baseline.jsonc	Baseline updated to include origin selection ranges for import type nodes.
testdata/baselines/reference/fourslash/goToDefinition/goToTypeDefinition4.baseline.jsonc	Adds origin selection range for type definition reference.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionTypeOnlyImport.baseline.jsonc	Adds origin selection range for type-only import symbol.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionSimple.baseline.jsonc	Marks origin selection ranges on constructor calls.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionSignatureAlias_require.baseline.jsonc	Adds origin selection range for require alias references.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionShorthandProperty01.baseline.jsonc	Adds origin selection range for shorthand property.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionOverriddenMember8.baseline.jsonc	Marks override keyword origin selection.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionMultipleDefinitions.baseline.jsonc	Wraps multi-part marker span with selection markers.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionJsxNotSet.baseline.jsonc	Adds origin selection for JSX component reference.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionJsModuleNameAtImportName.baseline.jsonc	Adds origin selection range for JS module import name references.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionJsModuleName.baseline.jsonc	Adds origin selection range for module string literal.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionJsDocImportTag5.baseline.jsonc	Adds selection brackets inside JSDoc import tag parameter type.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionJsDocImportTag4.baseline.jsonc	Adds selection brackets in JSDoc import tag.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionImports.baseline.jsonc	Marks origin selection ranges for imported identifiers.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionImportedNames9.baseline.jsonc	Adds origin selection for destructured import usage.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionImportedNames8.baseline.jsonc	Adds origin selection around import specifier.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionImportedNames7.baseline.jsonc	Adds origin selection for default import reference.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionImportedNames6.baseline.jsonc	Adds origin selection for require alias import.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionImportedNames5.baseline.jsonc	Adds selection for export alias.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionImportedNames4.baseline.jsonc	Adds selection for imported alias.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionImportedNames3.baseline.jsonc	Adds selections for imported class references.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionImportedNames2.baseline.jsonc	Adds selection for imported class specifier.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionImportedNames11.baseline.jsonc	Adds selection for destructured require alias.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionImportedNames10.baseline.jsonc	Same as above for different test variant.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionImportedNames.baseline.jsonc	Adds selection for re-export specifier.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionImport1.baseline.jsonc	Adds selection around module string in import.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionExternalModuleName9.baseline.jsonc	Adds selection around external module string.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionExternalModuleName8.baseline.jsonc	Same pattern for export list.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionExternalModuleName7.baseline.jsonc	Same for import list.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionExternalModuleName6.baseline.jsonc	Adds selection for star import with pattern.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionExternalModuleName3.baseline.jsonc	Adds selection for require module string.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionExternalModuleName2.baseline.jsonc	Adds selection for relative module path in require.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionExternalModuleName.baseline.jsonc	Adds selection for relative module path with comment marker.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionDestructuredRequire2.baseline.jsonc	Adds selection for destructured require identifier.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionDestructuredRequire1.baseline.jsonc	Same for util require.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionDecorator.baseline.jsonc	Adds origin selection for decorator identifiers.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionClassConstructors.baseline.jsonc	Adds origin selection for class constructor references.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionCSSPatternAmbientModule.baseline.jsonc	Adds selection around CSS module import string.
testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionAcrossMultipleProjects.baseline.jsonc	Adds selection for cross-project reference.
testdata/baselines/reference/fourslash/goToDefinition/findAllRefsForDefaultExport.baseline.jsonc	Adds origin selection for default export reference.
testdata/baselines/reference/fourslash/goToDefinition/definition01.baseline.jsonc	Adds selection to external module path.
testdata/baselines/reference/fourslash/goToDefinition/definition.baseline.jsonc	Same change for variant.
testdata/baselines/reference/fourslash/goToDefinition/declarationMapsGoToDefinitionSameNameDifferentDirectory.baseline.jsonc	Adds origin selections for class and property in declaration map scenario.
testdata/baselines/reference/fourslash/goToDefinition/declarationMapsGoToDefinitionRelativeSourceRoot.baseline.jsonc	Adds origin selection for method name.
testdata/baselines/reference/fourslash/goToDefinition/declarationMapGoToDefinition.baseline.jsonc	Adds origin selection for method name (non-relative source root).
internal/project/untitled_test.go	Updates ProvideDefinition call to new signature with capabilities param.
internal/lsp/server.go	Passes client definition capabilities to LanguageService for definition/typeDefinition.
internal/ls/utilities.go	Adds toContextRange helper for context ranges (origin selection support).
internal/ls/findallreferences.go	Separates TextRange creation from LSP range construction; renames helper.
internal/ls/definition.go	Core logic: ProvideDefinition / ProvideTypeDefinition now produce LocationLinks with originSelectionRange when supported.
internal/fourslash/tests/gen/*.go	Numerous test updates: adapt to new VerifyBaselineGoToDefinition signature and origin selection range expectations.
internal/fourslash/fourslash.go	Adds default definition capabilities; rewrites VerifyBaselineGoToDefinition to handle LocationLinks and optional origin selection range.
internal/fourslash/baselineutil.go	Supports optional additional (origin) location in baselines replicating Strada behavior.
internal/fourslash/_scripts/convertFourslash.mts	Script updated to emit new Go calls including originSelectionRange boolean parameter and boundSpan handling.

[DanielRosenwasser]

Nice, thanks for tackling this!