Convert the code in `scripts/modules/animsys_refactor.py` from the legacy Actions API to the current API. The code was made for very old rigs (2.70 and older, last updated for Caminandes in 2014). The updated code seems to work on a Caminandes test file, and produces the same logging on the terminal as in Blender 4.3 (before slotted Actions). No functional changes. This is part of #146586 Pull Request: https://projects.blender.org/blender/blender/pulls/147060