Blender Git Loki

Cleanup: grease pencil app-template versioning

- Remove check for screens being None as this would raise an error.
- Replace loop over `area.spaces` with `area.spaces.active`.
- Loop over grease pencil data directly instead of accessing
through the scenes objects.
- Split versioning into functions.
- Use `update_factory_startup_*` prefix for function names
as this isn't versioning existing files.