When appended collections are instantiated in viewlayers, do not add to
viewlayers collections children of other instantiated collections.
This default behavior is required for proper copy/paste behavior. If
previous behavior needs to be brought back for regular append operation,
this can be decided and done, but think this default behavior also makes
sense in normal append case.
part of T91414: Unify link/append between WM operators and BPY context
manager API, and cleanup usages of `BKE_library_make_local`.
581fb2da10