Enable Per-display support on MagnificationController.

Refactor
1. Create DisplayMagnification to support multi-display
2. Using PooledLambda to simplify the existing code

Bug: 112273690
Test: MagnificationControllerTest, MagnificationGestureHandlerTest and
Manual test.

Change-Id: I19436b4671421dc58c0036e55f75178c1f413e9e
3 files changed