Push drag-resize mode to the client

The goal of this CL is to remove RELAYOUT_RES_DRAG_RESIZING_DOCKED and
RELAYOUT_RES_DRAG_RESIZING_FREEFORM, which is a step to make relayout an
oneway binder call.

When the resize mode is changed at the server side, the server will send
the new mode to the client via IWindow#resized, so the client doesn't
need to obtain the resize mode from the flags returned from relayout.

Bug: 161810301
Test: Perform drag-resize and drag-move on a freeform task and see if
      there is any unexpected behavior.
Change-Id: I450abc113932b6c1dc0ce0e2b76bebdf85a60777