No functional changes intended.
This patch moves the relevant keying set code from editors to animrig.
All functions are in the animrig namespace, and as such have lost their
`ANIM_` prefix.
Other than that, the code has been moved as is into `animrig/intern/keyingsets.cc`
Note that I also had to move `id_frame_has_keyframe` and `fcurve_frame_has_keyframe`.
I moved that into `ANIM_keyframing.hh` and `ANIM_fcurve.hh` since I found that more fitting.
Due to Windows defining `DELETE` as macro I had to rename `ModifyKeyMode::DELETE`
to `ModifyKeyMode::DELETE_KEY`
As a result of this two includes from animrig to editors were removed.
This is part of #121336
Pull Request: https://projects.blender.org/blender/blender/pulls/129980
b38d8ecb86