feat: Select project for repository

Description

• In this MR I've implemented requesting repositories list from the client and building repository tree based on that data
• Current MR allows to assign project for multi-remote repository. LS will persist data provided by the client.

Related Issues

References gitlab-org/editor-extensions/gitlab-lsp#1444

How has this been tested?

1. Enable the feature flag in settings.json: "gitlab.featureFlags.useLanguageServerRepositories": true
2. Run extension in dev host
3. Check Workflow tab and specifically "Issues and Merge Requests"
4. It should render the list of repositories with the selected project (if there is a single project for repository)
5. In case of the multi remote repository you should be able to assign project to repository clicking the multi remote item and then selecting item from the list
6. You should also be able to clean up the selection
7. Selection should persist across the sessions (implemented in this MR on the LS side but can be tested in the extension).

• ⚠️ Manually assigning project is not implemented here (Follow up)
• ⚠️ Assigned issues/MRs wont load yet - need to provide project id from the LS (Follow up)

What CHANGELOG entry will this MR create?

• fix: Bug fix fixes - a user-facing issue in production - included in changelog
• feature: New feature - a user-facing change which adds functionality - included in changelog
• BREAKING CHANGE: (fix or feature that would cause existing functionality to change) - should bump major version, mentioned in the changelog
• None - other non-user-facing changes