Launcher: Remove the Launcher app, and all hacks in support of it

The Launcher's functionality has been replaced by the app shortcuts in
the system menu.

There were various window management hacks to ensure that the launcher
stayed below all other windows while also being movable, etc.

Servers/WindowServer/WSClientConnection.cpp

@@ -215,9 +215,6 @@ bool WSClientConnection::handle_message(const WSAPI_ClientMessage& message, cons
         case WSAPI_WindowType::Menubar:
             ws_window_type = WSWindowType::Menubar;
             break;
-        case WSAPI_WindowType::Launcher:
-            ws_window_type = WSWindowType::Launcher;
-            break;
         case WSAPI_WindowType::Invalid:
         default:
             dbgprintf("Unknown WSAPI_WindowType: %d\n", message.window.type);