We will move much of the git code to synchronous execution. When the
git_extension_wrapper receives a new repository, the repository is most
likely not initialized yet. We can wait for the initialization with
repository.status().

Lets start with fully encapsulating the `Repository` in the wrapper.
We should only consider making it a part of the public interface if
we start exposing too many `Repository` methods.

The bulk of this commit is changing tests so they can handle not having
access to the rawRepository.

And add integration tests which use actual running extension to validate
that we can select the repositories. The new methods have the same
purpose as the now-deprecated `getCurrentWorkspaceFolder` and
`getCurrentWorkspaceFolderOrSelectOne`.

This will enable us to attach logic to repositories in the future.
For example, we'll add GitLab API service to each repository to simplify
how we call API.

When the git extension got disabled, we called dispose() on the wrapper.
This dispose() method removed the listener that should have listened on
when the git extension gets enabled again.
The solution for this problem was to separate the enablement listener.

We were mistakenly showing the "Could not get Git Extension" message
during every extension startup.

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

The `protocol` attribute was only ever used in tests, omitting it
simplifies the interface and tests at no cost. The attribute can be
easily introduced in the future if we need it.

The only client of the parseGitRemote function is gitService and it took
the returned array and turned it into an object anyway. Returning object
allows us to annotate the parameters instead of relying on the index. We
will also be able to crate a return type once we migrate to TS

There has been only one usage without the instanceUrl. It was in GitService and it
was much better relplaced with url.parse. That will allow us to have stronger
type definition in TS.

find the intersection of git remotes hostnames and PATs hostnames,
and if the intersection has exactly one hostname,
use that as the instanceUrl, otherwise just do nothing.

This change introduces Jest test framework to run our unit tests.

Implementing integration and unit tests using mocha and adding two
documents that describe the testing strategy and guide how to write
new tests.