Dedicated Smartspace handling for Dreams.

This changelist introduces a separate DreamSmartSpaceController to handle smartspace sessions for dreams. The separation from the lockscreen logic allows for dream specific filtering and loading logic.

Test: atest DreamSmartspaceControllerTest LockscreenPreconditionTest LockscreenTargetFilterTest
Bug: 217562997
Change-Id: Ib857cfaf9614c27810110e569525ae6d88613429