Add traces to aid onScreenTurnedOn latency debugging

+ Adding traces to HingeSensorAngle provider (it seems it takes >10ms to initialize on the ui thread)
+  Adding traces to Keyguard display manager: show and hide presentation together account for 130ms, and should definitely be improved
+ Removed PowerManager import as style checks complained

Bug: 197515205
Test: recorded a perfetto trace and made sure those are there
Change-Id: I38def9d0503638a4647e097c9c5974660e0f8cd0