repl: Add restart kernel action and improve shutdown (#16609)

- Implement restart kernel functionality
- Clean up shutdown process to properly drop messaging and exit status
tasks
- Refactor kernel state handling for better consistency

Closes #16037

Release Notes:

- repl: Added restart kernel action
- repl: Fixed issue with shutting down kernels that are in a failure
state

crates/quick_action_bar/src/repl_menu.rs

@@ -173,8 +173,6 @@ impl QuickActionBar {
                             url: format!("{}#change-kernel", ZED_REPL_DOCUMENTATION),
                         }),
                     )
-                    // TODO: Add Restart action
-                    // .action("Restart", Box::new(gpui::NoAction))
                     .custom_entry(
                         move |_cx| {
                             Label::new("Shut Down Kernel")
@@ -189,6 +187,20 @@ impl QuickActionBar {
                             }
                         },
                     )
+                    .custom_entry(
+                        move |_cx| {
+                            Label::new("Restart Kernel")
+                                .size(LabelSize::Small)
+                                .color(Color::Error)
+                                .into_any_element()
+                        },
+                        {
+                            let editor = editor.clone();
+                            move |cx| {
+                                repl::restart(editor.clone(), cx);
+                            }
+                        },
+                    )
                     .separator()
                     .action("View Sessions", Box::new(repl::Sessions))
                     // TODO: Add shut down all kernels action
@@ -305,6 +317,15 @@ fn session_state(session: View<Session>, cx: &WindowContext) -> ReplMenuState {
     };
 
     let menu_state = match &session.kernel {
+        Kernel::Restarting => ReplMenuState {
+            tooltip: format!("Restarting {}", kernel_name).into(),
+            icon_is_animating: true,
+            popover_disabled: true,
+            icon_color: Color::Muted,
+            indicator: Some(Indicator::dot().color(Color::Muted)),
+            status: session.kernel.status(),
+            ..fill_fields()
+        },
         Kernel::RunningKernel(kernel) => match &kernel.execution_state {
             ExecutionState::Idle => ReplMenuState {
                 tooltip: format!("Run code on {} ({})", kernel_name, kernel_language).into(),