db4d9067d0
As described in #135095, this adds a "mirror" option to the "Join as Shapes" and "Update from Objects" operators, and additional menu items with the option enabled. Like the operators, this is a convenience feature that's functionally the same as selecting all shape keys with changed data and running the existing "Flip" operator. Pull Request: https://projects.blender.org/blender/blender/pulls/144098