Git commit modal branch list (#26417)

Closes #26273

Release Notes:

- git: Fixes opening the branch selector in the commit modal with
cmd-option-b
- git: Truncates the branch selector in the commit modal

crates/workspace/src/modal_layer.rs

@@ -1,6 +1,7 @@
 use gpui::{AnyView, DismissEvent, Entity, FocusHandle, Focusable as _, ManagedView, Subscription};
 use ui::prelude::*;
 
+#[derive(Debug)]
 pub enum DismissDecision {
     Dismiss(bool),
     Pending,