Add hack to make quit action work everytime

Kirigami's AbstractApplicationWindow already registers a Shortcut for the standard quit action. However we also want to have the action with the shortcut displayed so we need to set it on our action. To solve this conflict, one of them has to be disabled. Disabling our action does not work because it would not longer be possible to interact with the created item corresponding to it. So we need to disable the shortcut inside Kirigami.

Closes #1 (closed)