`loading` MR Widget actions are not disabled in mobile view, which could lead to clicks which should be impossible

In !101828 (merged), I added an action to the Closed Widget that causes some asynchronous requests to be made.

While these requests are happening, the action's loading value is set to true.

In the "standard" view, a loading Widget action is disabled:

However, in the small/mobile view, these actions are listed in a dropdown menu that does not disable them:

In the mobile view, menu items are always interactive, which could potentially lead to multiple clicks during pending requests.

We should map the same "disabled" state from the desktop view to the mobile-friendly actions menu.