A simple implementation of the git.clone command for the configured
instances.
It also includes a credential provider that can clone the repository
without user input using the access token

See merge request gitlab-org/gitlab-vscode-extension!172

Relates to #222

This change starts fetching position for each discussion and then
it displays the discussions on diffs using the native VS Code API

We test that the pipeline status bar item gets correcly populated.

We were using version 1 which doesn't have type definitions. The upgrade
is trivial and hence easier than writing our own type definitions.