[Relayout] Part 1: Define flags

Introduce flags for relayout.
Also, refactor the existing one as deprecated,
as we don't expect to use it going forward.

Bug: 238252288
Flag: EXEMPT : DeviceConfig: Exempt : Flags definition
Test: NA
Change-Id: I76d6b2974bea7f1c5ea9d3b7e25315afb07d6c1b