debugger: Remember pane layout from previous debugger session (#28692)

This PR makes a debugger's pane layout persistent across session's that
use the same debug adapter.

Release Notes:

- N/A

---------

Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>
Co-authored-by: Cole Miller <m@cole-miller.net>

crates/debugger_ui/src/tests/debugger_panel.rs

@@ -81,6 +81,8 @@ async fn test_basic_show_debug_panel(executor: BackgroundExecutor, cx: &mut Test
         })
         .await;
 
+    cx.run_until_parked();
+
     // assert we have a debug panel item before the session has stopped
     workspace
         .update(cx, |workspace, _window, cx| {
@@ -229,6 +231,8 @@ async fn test_we_can_only_have_one_panel_per_debug_session(
         })
         .await;
 
+    cx.run_until_parked();
+
     // assert we have a debug panel item before the session has stopped
     workspace
         .update(cx, |workspace, _window, cx| {
@@ -1052,6 +1056,8 @@ async fn test_debug_panel_item_thread_status_reset_on_failure(
         }))
         .await;
 
+    cx.run_until_parked();
+
     let running_state = active_debug_session_panel(workspace, cx).update_in(cx, |item, _, _| {
         item.mode()
             .as_running()

crates/debugger_ui/src/tests/variable_list.rs

@@ -1538,6 +1538,8 @@ async fn test_variable_list_only_sends_requests_when_rendering(
         })
         .await;
 
+    cx.run_until_parked();
+
     let running_state = active_debug_session_panel(workspace, cx).update_in(cx, |item, _, _| {
         let state = item
             .mode()