This change adds support for Version Controlled projects in language server.
Version Control supports operations:
- `init` - initialize VCS for a project
- `save` - commit all changes to the project in VCS
- `restore` - ability to restore project to some past `save`
- `status` - show the status of the project from VCS' perspective
- `list` - show a list of requested saves
# Important Notes
Behind the scenes, Enso's VCS uses git (or rather [jGit](https://www.eclipse.org/jgit/)) but nothing stops us from using a different implementation as long as it conforms to the establish API.
