Hook-up shell-transitions to DisplayChangeController rotation

A direct display rotation goes through requestStartTransition
instead of "remote rotation". As a result, we need to hook-up
the handleRequest to shell's displayChangeController so that
other shell components (like task organizers) have a chance
to calculate new bounds for their organized windows.

Bug: 206872147
Test: via logging, ensure that shell DisplayChangingListener
      is fired during a display rotation.
Change-Id: I839ebd28d4947ed3ec41d48724702d035f726f11