Move animation bounds into PipBoundsState

Moves mTemporaryBounds and mAnimatingToBounds into
a new state class for animations.

Bug: 169373982
Test: com.android.wm.shell.pip
Test: drag, move, resize, fling, dismiss working fine
Change-Id: Ie487f0cad2a1b2c2e5efc4d0404c8812b2f6c8ff