[Feature request] MacOS Images

[webbertakken]

Context

Right now unity-builder is using MacOS runners to install Unity Editor on the fly.
The reason for it is that MacOS doesn't run from docker images. Or didn't...

Suggested solution

Since then there's been a fair bit of development.

Collecting links here:

Discussion

• HostProcess containers for macOS containerd/containerd#5525
• https://stackoverflow.com/questions/40824547/docker-image-running-a-mac-os-x-installation

Possible solutions

• https://github.com/sickcodes/Docker-OSX
• https://github.com/darwin-containers

We should at some point decide that docker for MacOS is good enough and pick one of the technologies.

Considered alternatives

Keep using on the fly Unity Editor installs.

Additional details