Add DCAT registration remediation

[florelis]

Summary of the Pull Request

To remediate the case where the registration key gets deleted, we re-set the key on every launch.

PR Checklist

• Closes: Link to issue #xxx
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated if needed and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated if needed
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

I added the remediation to both wslservice and wslaservice, near the end of the OnServiceStarting(). The registration function writes to the registry without checking, as we would want to update the version if it is wrong for some reason.
I added an option to set the registration version to 0.0.0.0, which can be used for the initial installation.

Pending:

• Tests
• Handle errors when writing to the registry

Validation Steps Performed

[Copilot]

Pull request overview

This PR adds a remediation to re-register WSL components with DCAT on every service launch, addressing cases where the DCAT registration registry key is missing or incorrect.

Changes:

• Call wsl::windows::common::helpers::RegisterWithDcat() during startup of both wslservice and wslaservice.
• Add RegisterWithDcat() implementation to src/windows/common/helpers.* to write the DCAT registry value.
• Introduce a DCAT_REGISTRATION_KEY compile definition from CMake for the registry path.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/windows/wslaservice/exe/ServiceMain.cpp	Calls DCAT registration during WSLA service startup.
src/windows/service/exe/ServiceMain.cpp	Calls DCAT registration during WSL service startup; adds include.
src/windows/common/helpers.hpp	Declares RegisterWithDcat() helper API.
src/windows/common/helpers.cpp	Implements DCAT registry write logic.
CMakeLists.txt	Adds compile definition for DCAT_REGISTRATION_KEY.