Previously we imported the Oid type (for Git object identifiers) different places. This was confusing, and also meant that upgrading a dependency (radicle-git-ext) broke, because two types with the same name imported from different versions of the same crate are different types.

Change this so that radicle::git::Oid is the one true Oid type we use.

Signed-off-by: Lars Wirzenius liw@liw.fi