Make AOD transitions more calm

- Disable unfurling of notifications and alpha blend them instead
- Fix alpha blend of notifications when there is a pulsing notification active
- Make notification icons animate in/out
- Fix alpha blend of LockIconView
- Make KeyguardBottomArea fade out
- Add new flag NEW_AOD_TRANSITION

Spec: https://direct.googleplex.com/#/spec/285230003
Bug: b/290738624
Test: atest NotificationStackScrollLayoutTest StackScrollAlgorithmTest
Change-Id: If44c2088598c4a5bb954149c412050c6cb1a1f54