Clean up "languageServer" feature flag

Problem to solve

The languageServer feature flag has been defaulted to true for some time now. The Language Server is now a core dependency of the extension, not an optional feature. Keeping this feature flag maintains legacy code suggestions implementation and other legacy feature implementations that are no longer necessary.

Solution proposal

Remove the languageServer feature flag and all associated legacy implementations. This will simplify the codebase and ensure all users benefit from the Language Server implementation.

Acceptance criteria

  • Remove gitlab.featureFlags.languageServer configuration entry from relevant package.json files
  • Remove feature flag references from the extension codebase
  • Remove legacy code suggestions implementation
  • Remove other legacy feature implementations that were conditional on this flag
  • Update documentation if needed

Links / references

Edited by Mohammed Osumah