[VSCode] Use Language Server to serve code suggestions in the Web IDE

Problem to solve

The VSCode Extension uses a legacy implementation of Code Suggestions in the Web IDE. This version of Code suggestions is outdated and doesn't include advanced context features such as Open Tabs Context.

Proposal

After delivering gitlab-org/editor-extensions/gitlab-lsp#1365 (closed), we should replace the Legacy Code Suggestions implementation with the Language Server implementation.

Acceptance criteria

• Ensure that the Extension provides all the configuration parameters expected by the web version of the Language Server.
• Make sure that only Code Suggestions is provided by the Language Server but the legacy chat implementation is still used in the Web IDE.

Further details

Links / references