Add branch to git panel (#24485)

This PR adds the branch selector to the git panel and fixes a few bugs
in the repository selector.

Release Notes:

- N/A

---------

Co-authored-by: ConradIrwin <conrad.irwin@gmail.com>
Co-authored-by: Conrad <conrad@zed.dev>

crates/zed/Cargo.toml

@@ -126,7 +126,6 @@ url.workspace = true
 urlencoding = "2.1.2"
 util.workspace = true
 uuid.workspace = true
-vcs_menu.workspace = true
 vim.workspace = true
 vim_mode_setting.workspace = true
 welcome.workspace = true