[VSCode] Run Web IDE code suggestions test in the VSCode extension pipeline

Problem to solve

It's easy to introduce changes to the VSCode extension that break compatibility with the Web IDE and engineers don't have a feedback mechanism to detect these breaking changes before the extension is release.

Proposal

Run the Web IDE integration tests that exercise the code suggestions feature in the GitLab VSCode Extension's CI pipeline to detect breaking changes in the development process.

Further details

Links / references

[WebIDE] Implement an integration test that ver... (gitlab-web-ide#464 - closed)