Centralize rotation control to DisplayRotation

- Move seamless rotation logic. The scattered conditions
  (mayRotateSeamlessly) are also combined into shouldRotateSeamlessly.
- Move DisplayContent#updateRotationUnchecked and the related fields.
- Consolidate DisplayContent#updateOrientationFromAppTokens and
  DisplayRotation#setCurrentOrientation to DR#updateOrientation.

Bug: 117593656
Test: go/wm-smoke
Test: atest DisplayContentTests DisplayPolicyTests DisplayRotationTests

Change-Id: Ifd978a20a2773a39000a90edf683e6459adf0d2d