Add logs for PiP exclusion bounds

- Add extra logs when the PiP exclusion bounds, usually listened by back
  gesture in SysUI, is updated
- Update the internal interface for adding/removing the listener

Flag: EXEMPT logonly
Bug: 407227077
Test: atest WMShellUnitTests:PipBoundsStateTest
Test: Verify the logs are properly printed out
Change-Id: I2c120f508f8721121bb9300e49f4c43086889a14