Add Github Workflow based CI

[qno]

This is now an exact drop-in replacement for Azure CI based on Github Workflow.

It builds on every push and merge request but creates releases only if the development branch gets build. The CI runs are accessible under https://github.com/AriaSalvatrice/AriaVCVModules/actions. I'm not sure why it doesn't run on your repo in this pull request context already, not sure if you have to enable something on your repo. Afaik on my side I didn't need to enable anything for this to work.

For this MR you can see it here - https://github.com/qno/AriaVCVModules/actions/runs/313616477

Release assets are still getting published to the AzureCI release tag. If you wish to change this, you would have to create a new release in Github and then change the value of release-tag in the env section to the new tag.

I think a huge advantage of this is that contributors automatically also get CI builds on their forks without the need to create and setup an account on Azure.

You can do whatever you want with this MR, I just did it to learn more about Github workflow.

Additional changes:

• Azure CI definition deleted
• azure-win-dist Makefile target deleted as plugin.mk gets now patched in CI process
• set plugin version based on existing version in plugin.json e.g. "version": "1.7.1" becomes "version": "1.7.1-42eb7d6" instead of "version": "1.0.42eb7d6"

[AriaSalvatrice]

Thank you! I will test it and integrate it after my next release, since right now I'm depending on AzureCI builds to beta test a module under heavy development