Allows patches to have their state updated to `Merged` with a `git push`
to the default branch.
Currently, due to the limitations of the COB store, this requires a
linear search through all patches. This will eventually become a problem
when projects have thousands of patches, so we should look into
long-term solutions.
This adds the ability to the git-remote-helper to open and update
patches via a `git push` to the magic ref `refs/patches` and
`refs/heads/patches/<patch-id>`.
The main change is that we had to move away from offering the `connect`
capability in the remote helper, to offering `push` and `fetch`
individually.
To get a feel for how this works, see the `rad-patch-via-push.md`
example.
Alexis Sellier