Rework Fullscreen StatusBar to only toggle on a real swipe

Inspired by a SlimRoms commit from kufikugel:
https://github.com/SlimRoms/frameworks_base/commit/274c854ea2acb03dc193c24e69829ece9125020f
Thanks for that!

Change-Id: I26f3df20a77066625072f1741196789a5cd3ff9d