Add latest safe region bounds on the activity in the dump

- Since a WindowContainer may not have some assigned safe region bounds
  but an activity can still be within the safe region bounds because of
safe region bounds being present on the closest ancestor
WindowContainer, dump the safe region bounds being used by the activity
for easy debugging.

Bug: 380132497
Bug: 368408934
Flag: com.android.window.flags.safe_region_letterboxing
Test: m
Change-Id: Ibe82177d911f68147878cc210f227e454e3f8564