Move Rigify from the external add-ons repository into
`scripts/addons_core`.
This commit adds Rigify, from the latest revision in [the add-ons
repo][addons]. It contains work by the following authors:
202 Alexander Gavrilov
67 Campbell Barton
58 Nathan Vegdahl
31 Lucio Rossi
24 Demeter Dzadik
10 Brecht Van Lommel
8 Dalai Felinto
7 Bastien Montagne
7 Sybren A. Stüvel
5 Damien Picard
4 meta-androcto
3 Ines Almeida
2 Jonathan Smith
2 ZanQdo
1 Aaron Carlisle
1 Andrej730
1 Hans Goudey
1 Luca Bonavita
1 Patrick Huang
1 Sergey Sharybin
1 Thomas Dinges
For the full history see the read-only [add-ons repository][addons].
Rigify has existed briefly as an extension on the extensions platform,
and commits were made to Rigify's extension repository (which is
different from the above-mentioned add-ons repository). That repository
will be deleted soon. Its commits that actually changed Rigify will be
committed as followups to this commit. Some commits were necessary to
turn the add-on into an extension; those will be ignored, as they're no
longer relevant.
[addons]: https://projects.blender.org/blender/blender-addons/src/rigify
Ref: !121825
Pull Request: https://projects.blender.org/blender/blender/pulls/123833
