NavBar/Pie: optimize clear all recents key
- navbar/pie/recents reside in the same process so we can use direct
method calls instead of using broadcasts which bring too much overhead
- make sure to update only key icon on navigation icon hints update
- send broadcasts to ModHwKeys only when state changes
This speeds up the processing of this feature and reduces CPU
requirements, plus avoids misbehavior that can be caused by broadcasts
related delayed processing