Add TransparencyPolicy state to dump

Adding TransparentPolicy state to LetterboxUiController#dump().

Flag: EXEMPT small debug change
Fix: 358028241
Test: m
Test: Run `adb shell dumpsys activity top-resumed` and check
      if TransparentPolicy state is present

Change-Id: I6c17958a4f47241545ef59e1bd68c5f4a49ef730