Add GitHub workflow for wheel and sdist building and upload

[djhoese]

Based on discussion in #22

This is a basically an almost straight copy/paste from vispy's github workflow which we've only used once or twice. I decided to use vispy's workflow instead of some of my other projects that have fancier workflows because vispy is closer to datoviz's build process with freetype and other stuff. We'll see how this goes.

There are a lot of steps I see in the install from source documentation and I'm not sure how many of them transfer to this 1:1. Also, this has the "cibuildwheel" tool to create all the wheels which means some of the build commands have to go into environment variables. It might be easier to put these into scripts (ex. <repos root>/ci/). I'm going to focus on linux first and see if we can get that working.

This won't show up in datoviz's Actions until merged so if you want to see the current status you can go here: https://github.com/djhoese/datoviz/actions

[djhoese]

Ah I see you have a "wheel" target in your manage.sh script. I could try using that maybe if you think that would work @rossant

[rossant]

Thanks @djhoese !

Yes, these are the commands that should be used to create binary wheels:

• Linux: ./manage.sh wheel
• macOS: ./manage.sh wheel
• Windows: manage.bat wheel