The insert key function in `animrig/keyframing.cc` took a `ReportList`
argument which it used to print messages in case of failures.
Instead this now returns a `CombinedKeyingResult` and the caller is
responsible for creating reports out of that.
To make that simpler the `ID` argument has been changed from a pointer to a reference.
The calling functions now make sure that it's not a `nullptr`.
This has the effect that there will be less messages printed in the Info panel when e.g. inserting keys with a keyingset.
This still doesn't make an error message pop up though.
Related to #119776
Pull Request: https://projects.blender.org/blender/blender/pulls/120784
c30647a6fc