Currently the `GitClient` accepts a generic parameter for determining
whether the `githubToken` should be set or not. This worked fine so far
in terms of distinguishing between an authenticated and
non-authenticated git client instance, but if we intend to conditionally
show methods only for authenticated instances, the generic parameter
is not suitable.
This commit splits up the `GitClient` into two classes. One for
the base logic without any authorization, and a second class that
extends the base logic with authentication logic. i.e. the
`AuthenticatedGitClient`. This allows us to have specific methods only
for the authenticated instance. e.g.
* `hasOauthScopes` has been moved to only exist for authenticated
instances.
* the GraphQL functionality within `gitClient.github` is not
accessible for non-authenticated instances. GraphQL API requires
authentication as per Github.
The initial motiviation for this was that we want to throw if
`hasOAuthScopes` is called without the Octokit instance having
a token configured. This should help avoiding issues as within
3b434ed94d
that prevented the caretaker process momentarily.
Additionally, the Git client has moved from `index.ts` to
`git-client.ts` for better discoverability in the codebase.
PR Close#42468