Blender Git Loki

Merge branch 'master' into refactor-vertex-group-names

Fixes from review comments

Safer RNA object vertex group API (should fix issues reported by @Mets, thanks!)

Merge branch 'master' into refactor-vertex-group-names

Rename functions "for_read" -> "" and "for_write" -> "mutable"

Share implementation of vertex group retrieval

Merge branch 'master' into refactor-vertex-group-names

Fix issue with modifier vertex group utility-- tests pass

More fixes and cleanup

Merge branch 'master' into refactor-vertex-group-names

Add small API to retrieve vertex group indices and lists from an ID

Move active index to geometry

Merge branch 'master' into refactor-vertex-group-names

Fix unused variable warning

Add comments, minor cleanup, remove debug statements

Merge branch 'master' into refactor-vertex-group-names

Refactor: Move vertex group names to object data (WIP)

As explained in T88951, the list of vertex group names is currently
stored separately per object, even though vertex group data is stored
on the geometry. This tends to complicate code and cause bugs,
especially as geometry is created procedurally and tied less closely
to objects.

This commit moves the storage of `bDeformGroup` to `Mesh`, `Lattice`,
and `bGPdata` instead of `Object`. In order to avoid dramatically
changing existing code, I introduced a helper function to access the
list of names given just the object.

TODO:
- Move the active group index to the object as well.
- Possibly move the Python API for vertex groups to object data.

Differential Revision: https://developer.blender.org/D11689