Separate rotationHint as different object of WindowBounds

Some WindowBounds object with different rotation would be ignore in
DisplayController#supportedBounds due to there already exists an object
with the same bounds.

Bug: 304284870
Test: open app then rotate tablet device to 90 or 270, close app and
monitor the closing target flying back to the expected position.
Flag: N/A

Change-Id: I97f070cfaf7c6243ae3cd95cb728f7041a3736d1