merging Craig's GSoC 2023 auto-hinter code

[Werner LEMBERG]

Craig and others,


have a look at the Merge Request

  https://gitlab.freedesktop.org/freetype/freetype/-/merge_requests/316

This is a completely cleaned-up version of Craig's
'gsoc-craig-2023-final' branch, ready for being included into
'master'.

I've heavily formatted the code to be in sync with other FreeType
code, removed some unused stuff, cleaned up code here and there, and
re-generated the commits in smaller logical chunks from scratch to
make them more comprehensible.  Hopefully, I haven't screwed up the
code while doing so.

Please check and test!


    Werner