When node input sockets are animated, they target the socket by index.
As a result, animation data needs to be updated whenever new sockets are
added (except when they're added at the end of the list). The code for
this is now extracted into its own versioning function, so that it can
be used for other versioning steps as well.
No functional changes.
Subdivision surface: Both geometry sockets renamed to "Mesh"
Points to Volume: Use "Points" and "Volume" names
Distribute Points on Faces: Use "Mesh" input name
These are meant to provide a hint to users which type each
node is meant to use.
Adds `source/blender/blendloader/intern/versioning_common.cc` and
`versioning_common.h` for version independent versioning functions.
I only placed `do_versions_add_region_if_not_found()` in there for now.
`blo_do_version_old_trackto_to_constraints()` could also be added, but
that's so old, I prefer keeping that in `versioning_legacy.c`.
