Only set window crop and position in relayout when fluid drag resizing

Setting the position and crop during relayout is causing flashes in
various transitions and it is only needed for fluid drag resizing. This
CL makes the following changes:

1. Checks if task is fluid drag resizing before setting the position and
   window crop of the surface in WindowDecoration#relayout
2. Uses shell transitions to apply the final change in a fluid drag and
   drag resize.

Bug: 315489329
Bug: 315487743
Bug: 315488702
Test: Testing transitions to make sure flash is gone and turning on
fluid resizing to make sure it is still functional.

Change-Id: I0122543bb7e8fd744f58edcf8b44038a5ce1a001