Blender Git Loki

Fix T82439: Crash moving collections between scenes

The original code for viewlayer collection flag syncing across moves
from D9158 didn't consider the case where the collection could no longer
be found in its original view layer (moving a collections betwen scenes).

The fix is to just check if the collection starts in the same scene as
it will be moved to before trying to do the flag syncing. I thought about
this for a while and tried a couple other solutions, but I couldn't come
up with a proper way to support syncing the layer collection flags across
scenes without making too many changes.

Differential Revision: https://developer.blender.org/D9568