Remove the `Action::binding_for_id()` method, as it is a bit dangerous,
only useful in a very specific situation, and can be removed altogether
with just a little bit of refactoring. This in turn made some other
functions a bit simpler too.
Almost no functional changes. The only change is that when through some
magic (aka data corruption or other bug) the Binding is no longer valid
for the animated ID's type, the IDs properties may still show as
animated in the interface.
Pull Request: https://projects.blender.org/blender/blender/pulls/121748
0caf6397df