Blender Git Loki

Bugfix [#24163] Unable to animate INSIDE a group node in the
compositor

This commit fixes the original bug reported here by adding some
methods to move the relevant F-Curves (and drivers) over to the new
Node-Tree's (i.e. group-node) AnimData. Animated nodes which
subsequently get grouped will still be able to animate as a result of
this commit.

TODO's:
- Ungrouping now will not yet merge the animation back (or at least
copy it)
- Buttons for nodes freshly grouped do not correctly show animated
status indicators for some reason, yet normal animation does