WindowServer+LibGUI: Make much of menu construction asynchronous

Creating a menu/menubar needs to be synchronous because we need the
ID from the response, but adding stuff *to* menus (and adding menus
to menubars, and menubars to windows) can all be asynchronous.

This dramatically reduces the amount of IPC ping-pong played by
each GUI application during startup.

I measured how long it takes TextEditor to enter the main event loop
and it's over 10% faster here. (Down from ~86ms to ~74ms)

Userland/Libraries/LibGUI/Menu.cpp

@@ -94,14 +94,14 @@ int Menu::realize_menu(RefPtr<Action> default_action)
         item.set_menu_id({}, m_menu_id);
         item.set_identifier({}, i);
         if (item.type() == MenuItem::Type::Separator) {
-            WindowServerConnection::the().add_menu_separator(m_menu_id);
+            WindowServerConnection::the().async_add_menu_separator(m_menu_id);
             continue;
         }
         if (item.type() == MenuItem::Type::Submenu) {
             auto& submenu = *item.submenu();
             submenu.realize_if_needed(default_action);
             auto icon = submenu.icon() ? submenu.icon()->to_shareable_bitmap() : Gfx::ShareableBitmap();
-            WindowServerConnection::the().add_menu_item(m_menu_id, i, submenu.menu_id(), submenu.name(), true, false, false, false, "", icon, false);
+            WindowServerConnection::the().async_add_menu_item(m_menu_id, i, submenu.menu_id(), submenu.name(), true, false, false, false, "", icon, false);
             continue;
         }
         if (item.type() == MenuItem::Type::Action) {
@@ -110,7 +110,7 @@ int Menu::realize_menu(RefPtr<Action> default_action)
             bool exclusive = action.group() && action.group()->is_exclusive() && action.is_checkable();
             bool is_default = (default_action.ptr() == &action);
             auto icon = action.icon() ? action.icon()->to_shareable_bitmap() : Gfx::ShareableBitmap();
-            WindowServerConnection::the().add_menu_item(m_menu_id, i, -1, action.text(), action.is_enabled(), action.is_checkable(), action.is_checkable() ? action.is_checked() : false, is_default, shortcut_text, icon, exclusive);
+            WindowServerConnection::the().async_add_menu_item(m_menu_id, i, -1, action.text(), action.is_enabled(), action.is_checkable(), action.is_checkable() ? action.is_checked() : false, is_default, shortcut_text, icon, exclusive);
         }
     }
     all_menus().set(m_menu_id, this);

Userland/Libraries/LibGUI/MenuItem.cpp

@@ -74,7 +74,7 @@ void MenuItem::update_window_server()
         return;
     auto& action = *m_action;
     auto shortcut_text = action.shortcut().is_valid() ? action.shortcut().to_string() : String();
-    WindowServerConnection::the().update_menu_item(m_menu_id, m_identifier, -1, action.text(), action.is_enabled(), action.is_checkable(), action.is_checkable() ? action.is_checked() : false, m_default, shortcut_text);
+    WindowServerConnection::the().async_update_menu_item(m_menu_id, m_identifier, -1, action.text(), action.is_enabled(), action.is_checkable(), action.is_checkable() ? action.is_checked() : false, m_default, shortcut_text);
 }
 
 void MenuItem::set_menu_id(Badge<Menu>, unsigned int menu_id)

Userland/Libraries/LibGUI/Menubar.cpp

@@ -49,7 +49,7 @@ void Menubar::notify_added_to_window(Badge<Window>)
     for (auto& menu : m_menus) {
         int menu_id = menu.realize_menu();
         VERIFY(menu_id != -1);
-        WindowServerConnection::the().add_menu_to_menubar(m_menubar_id, menu_id);
+        WindowServerConnection::the().async_add_menu_to_menubar(m_menubar_id, menu_id);
     }
 }
 

Userland/Libraries/LibGUI/Window.cpp

@@ -1075,7 +1075,7 @@ void Window::set_menubar(RefPtr<Menubar> menubar)
     m_menubar = move(menubar);
     if (m_window_id && m_menubar) {
         m_menubar->notify_added_to_window({});
-        WindowServerConnection::the().set_window_menubar(m_window_id, m_menubar->menubar_id());
+        WindowServerConnection::the().async_set_window_menubar(m_window_id, m_menubar->menubar_id());
     }
 }
 

Userland/Services/WindowServer/WindowServer.ipc

@@ -8,7 +8,7 @@ endpoint WindowServer
     create_menu([UTF8] String menu_title) => (i32 menu_id)
     destroy_menu(i32 menu_id) => ()
 
-    add_menu_to_menubar(i32 menubar_id, i32 menu_id) => ()
+    add_menu_to_menubar(i32 menubar_id, i32 menu_id) =|
 
     add_menu_item(
         i32 menu_id,
@@ -21,11 +21,11 @@ endpoint WindowServer
         bool is_default,
         [UTF8] String shortcut,
         Gfx::ShareableBitmap icon,
-        bool exclusive) => ()
+        bool exclusive) =|
 
-    add_menu_separator(i32 menu_id) => ()
+    add_menu_separator(i32 menu_id) =|
 
-    update_menu_item(i32 menu_id, i32 identifier, i32 submenu_id, [UTF8] String text, bool enabled, bool checkable, bool checked, bool is_default, [UTF8] String shortcut) => ()
+    update_menu_item(i32 menu_id, i32 identifier, i32 submenu_id, [UTF8] String text, bool enabled, bool checkable, bool checked, bool is_default, [UTF8] String shortcut) =|
 
     create_window(
         Gfx::IntRect rect,
@@ -49,7 +49,7 @@ endpoint WindowServer
 
     destroy_window(i32 window_id) => (Vector<i32> destroyed_window_ids)
 
-    set_window_menubar(i32 window_id, i32 menubar_id) => ()
+    set_window_menubar(i32 window_id, i32 menubar_id) =|
 
     set_window_title(i32 window_id, [UTF8] String title) => ()
     get_window_title(i32 window_id) => ([UTF8] String title)