Reordering layer nodes by drag-drop, move up/down, add new etc. swaps
layer attributes with wrong layers. This is due to mistake in map
`new_by_old_map`. Values of this map is used as indices in src array.
And keys are indices of dst array. Expected behavior is to copy attribute from
old position (`layer_i_old`) of src array to new position (`layer_i_new`) of
dst array. See: `array_utils::gather`.
Noticed during !141772.
Pull Request: https://projects.blender.org/blender/blender/pulls/141935
ef89c75382