Fixes to commit button in Git Panel (#24425)

Git Panel updates:

* Fixes commit/commit all button to work (and be disabled correctly in
merge conflict status)
* Updates keyboard shortcuts and sets focus on the button (enter now
does the same as click; tab cycles between editor and change list)


Closes #ISSUE

Release Notes:

- N/A *or* Added/Fixed/Improved ...

---------

Co-authored-by: Cole Miller <cole@zed.dev>

crates/git_ui/src/project_diff.rs

@@ -235,7 +235,7 @@ impl ProjectDiff {
                     .update(cx, |workspace, cx| {
                         if let Some(git_panel) = workspace.panel::<GitPanel>(cx) {
                             git_panel.update(cx, |git_panel, cx| {
-                                git_panel.set_focused_path(project_path.into(), window, cx)
+                                git_panel.select_entry_by_path(project_path.into(), window, cx)
                             })
                         }
                     })