Fix#11164 and involves a drive-by fix:
Kindle: Send Suspend/Resume event regardless of the screen saver state
If we get the events, it means stuff happened, we can't just only honor
it in the most common workflows ;).
This effectively reverts a tiny bit of #10426 (I was sort of expecting
this to be problematic at the time, and I most likely hadn't tested it).
Go through a dedicated sticky invisible widget instead of piggybacking
on ScreenSaverWidget, so that we behave if there are other InputContainers
in ScreenSaverWidget, or if there isn't any ScreenSaverWidget at all.
Fix#9911, fix#9955
