debugger: Select first stack frame with valid path (#32724)

This PR addresses an issue where we could get a stack frame list and
automatically select a stack frame that didn't have a valid path.
Causing a failure on Zed's end to select/update the active debug line.
The fix for this is selecting the first non-subtle stack frame that has
the optional path parameter.

We also made subtle stack frames move into their own collapsable list as
well.

Release Notes:

- debugger: Fix edge case where hitting a breakpoint wouldn't take you
to the active debug line

Co-authored-by: Remco Smits <djsmits12@gmail.com>

crates/debugger_ui/src/tests/stack_frame_list.rs

@@ -718,7 +718,7 @@ async fn test_collapsed_entries(executor: BackgroundExecutor, cx: &mut TestAppCo
                 stack_frame_list.entries()
             );
 
-            stack_frame_list.expand_collapsed_entry(1);
+            stack_frame_list.expand_collapsed_entry(1, cx);
 
             assert_eq!(
                 &vec![
@@ -735,7 +735,7 @@ async fn test_collapsed_entries(executor: BackgroundExecutor, cx: &mut TestAppCo
                 stack_frame_list.entries()
             );
 
-            stack_frame_list.expand_collapsed_entry(4);
+            stack_frame_list.expand_collapsed_entry(4, cx);
 
             assert_eq!(
                 &vec![