A refactoring internal to the `radicle` crate, with the goal of
making dependency on `git2` clearer and more controlled.
`radicle::raw` is changed from a complete re-export of `git2`
to a module that selectively re-exports (many) members of `git2`.
required to build the workspace (potentially breaking dependents
outside the workspace, but given just how many types are
re-exported, this seems unlikely).
In the future, no more `use git2::…` statements should be added
outside of `crates/radicle/src/git/raw.rs`. This is in an effort to
decrease dependence on `git2` in the future.
880634acd4
