Introduce DreamLog using LogBuffer.

This change introduces a DreamLogger which uses a LogBuffer. It also
logs the overlay animations state to this buffer.

Bug: 274804854
Test: atest DreamOverlayAnimationsControllerTest
Test: adb shell dumpsys activity service
com.android.systemui/.SystemUIService DreamLog -> verify overlay
animation states are dumpped

Change-Id: I0609cd20c47054de417367e054471ed66af57c41