Move the functions
* `BKE_pose_apply_action_selected_bones`
* `BKE_pose_apply_action_all_bones`
* and `BKE_pose_apply_action_blend`
out of the blender kernel and into animrig.
This will allow solving #126969 without having to include
animrig code in the blender kernel.
Pull Request: https://projects.blender.org/blender/blender/pulls/126978