Build all artifacts in a single MacOS environment

[petertrr]

Thanks for the cross-compilation support, it is possible to build artifacts for all the required platforms from a MacOS machine. This should be used for the release workflow. For the regular CI workflow, a Linux machine should be kept.

As a side task, automatic creation of a Github release should be made optional. Github supports creation of a tag and a release from the Web UI, which is oftentimes more convenient than manual creation of a tag from git.