Delay creation of ResizeVeil until it needs to be shown

Creating the resize veil when the window decoration is created is
somewhat wasteful (fullscreen/split tasks don't need it) and causes
jank.

Bug: 335975211
Test: manual - enter desktop from fullscreen from app handle drag,
handle menu button, also do freeform drag-resizing and maximize
resizing, all should show the veil as usual

Change-Id: I74a2acc1442efdc78993cf8fb9c852e2d8777b9f