Desktop: Bring back the "Tree" to show history branches

[BettyBei]

Please bring the "Tree view" back, like the following picture in the previous version.

[billygriffin]

Thanks for the request @BettyBei. This is a duplicate of https://github.com/desktop/desktop/issues/1634, and this is how we're thinking about improving our product-level communication going forward: https://github.com/desktop/desktop/issues/5398

Please follow along in #1634, and thanks again.