Blender Git Loki

UI/Assets: Disable undo for tree item buttons

Disables undo for:
* The tree row collapsing - which doesn't make sense to undo, isn't
supported by the undo system, and just triggers the confirmation
prompt when closing the file.
* Renaming items - While this may make sense in some cases, users of the
tree-view API can explicitly do an undo push. For asset catalogs it's
not supported.