LockscreenShadeTransitionController: extract logic of keyguard and scrims

The file size was starting to grow for this class, so started extracting
some of it.

Also implemented dumpable for the new classes for better tracking of state
in bug reports.

Bug: 227604286
Test: LockscreenShadeTransitionControllerTest.kt
Test: adb shell dumpsys activity service SystemUIService
Test: Manually
Change-Id: Iebd36726ebffdb9b6a37e742f69d7e5a80f25e6e