`BKE_main_ensure_invariants` was added in 1fae5fd8f6. The older
`ED_node_tree_propagate_change` was already implemented as a thin wrapper around
`BKE_main_ensure_invariants`. This patch removes the wrapper and calls the more
general function directly.
A new overload of `BKE_main_ensure_invariants` is added for the common case when
only a single data-block has been modified.
Pull Request: https://projects.blender.org/blender/blender/pulls/133048