Deleted branches with upstreams are revived via USE statements on read replicas

Branches that have been locally deleted from a read replica (with `call dolt_branch('-d')`) but that had an upstream tracking branch will be brought back to life when the replica resolves a reference to that branch name.

Not sure what the right behavior here is yet. The relevant variables are:

1) Does an upstream tracking reference exist locally, and should it after a `branch -d` call
2) Does the branch exist on the remote