When applying a pose asset created with 4.4 and later,
autokeyframing no longer worked. That is because poses
are generated without any FCurve groups now, and the
code assumed there to be an FCurve group for every
bone in the pose action.
I decided to remove that assumption and instead use
`BKE_action_find_fcurves_with_bones` which iterates
fcurves in an action+slot combination
and calls the provided callback. This is the logic that
the code to apply a pose uses as well.
Pull Request: https://projects.blender.org/blender/blender/pulls/139794
da2a09fe63