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/git_ui/src/git_ui.rs

@@ -5,6 +5,7 @@ use gpui::App;
 use project_diff::ProjectDiff;
 use ui::{ActiveTheme, Color, Icon, IconName, IntoElement};
 
+pub mod branch_picker;
 pub mod git_panel;
 mod git_panel_settings;
 pub mod project_diff;
@@ -12,6 +13,7 @@ pub mod repository_selector;
 
 pub fn init(cx: &mut App) {
     GitPanelSettings::register(cx);
+    branch_picker::init(cx);
     cx.observe_new(ProjectDiff::register).detach();
 }