Add scalafix rule to enforce clues in expect

[zainab-ali]

Calls to expect require clue to display error messages with diagnostics.

This scalafix rule is a linter rule that detects expect statements without clues. It can be added to .scalafix.conf:

rules = [
  "github:zainab-ali/weaver-test/EnforceCluesInExpect?sha=scalafix-enforce-clues"
]

Given that users will want to run this often (e.g. as part of their CI process), it would be better placed in typelevel-scalafix.