refactor: move git related logic to the WrappedRepository

This is an intermediate MR enabling #341 (closed).

The main goal of this MR could be summarized:

1. Make sure that the moment we wrap the repository (i.e. load it into the extension), it's got all the necessary data
   • this can be done by running await repository.status()
2. Now that we can rely on having repository data, migrate most of the methods from our custom GitService to WrappedRepository which is mostly calling methods on the Repository object from the VS Code Git Extension

This change almost completely removes the need for the extension running git binary directly. It also makes it easier to get the project namespace (new method get remote(): GitRemote) which we'll use in the next MR that is going to store project and merge requests in the WrappedRepository.

Related to #341 (closed)