Add github actions pipeline

[pauliyobo]

This is simply an experimentation to move Bookworm's CI to github actions.
Current runs seem to be up to 50% faster than appveyor builds, though I haven't implemented the full CI yet so we'll see.

[pauliyobo]

The GH actions pipeline is now on par with what appveyor does.
Going forward This will be the default CI pipeline.

[mush42]

@pauliyobo Awesome!