Complete conda-recipes Overhaul

[JacksonBurns]

Bringing this repo back to life!

Add GitHub Actions

GitHub provides free runners that can build these for us, so this PR will add those!
Specifically, we will build on all platforms and (eventually) all versions of Python that we want to support.

Technical Debt Cleanup

Many of the recipes in this repository are no longer needed since we now use the official builds, so this PR will remove them.

Here's the fate of all of the recipes:

• now on conda-forge/official, removed: gprof2dot, quantities, pyjulia, pydot, openbabel, mopac, julia, coolprop, cclib, cairo, cairocffi, lpsolve55, pyrdl
• unused, removed: zmats (was originally used for ARC), scoop, py3dmol, py2cairo, pixman, lpsolve, guppy, fontconfig, eigen, pyrms, diffeqpy
• sticking around, but just removed the windows stuff we don't use: symmetry

Status of remaining packages:

• symmetry: works on all platforms!

[JacksonBurns]

@hwpang @rwest this PR is ready now. We need to update the anaconda token on this repo (I will do this) and create a stable branch to merge into to trigger the builds and uploads (I will do this as well). Please let me know how the changes look!

[rwest]

Looks ok. I'm fine with removing the old stuff. Will this do multiple Python versions? Do we want it to?

[JacksonBurns]

Symmetry actually doesn't depend on Python. It is compatible with all versions of Python, in that way. There are no Python recipes left in this repo.

[hwpang]

LGTM too