tab_switcher: Add support for tab switcher in terminal panel (#9963)

tab switcher retrieves active pane from workspace, but that function is
not aware of Terminal Panel's pane. Thus in this PR we retrieve it
manually and use it as the active pane if terminal panel has focus.

Release Notes:

- Fixed tab switcher not working in terminal panel.

crates/terminal_view/src/terminal_panel.rs

@@ -591,6 +591,9 @@ impl TerminalPanel {
 
         Some(())
     }
+    pub fn pane(&self) -> &View<Pane> {
+        &self.pane
+    }
 }
 
 async fn wait_for_terminals_tasks(