GitHub Actions for templates

[rojepp]

Proposed Changes

Supply GitHub Actions workflows for generated projects.
Fixes #143.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• Build and tests pass locally
• I have added tests that prove my fix is effective or that my feature works (if appropriate)
• I have added necessary documentation (if appropriate)

[TheAngryByrd]

So now the question is, should be have different sets of CI available for people to choose from?

I do think eventually going with Github actions as the default when it comes out beta makes sense but probably want to leave the default as AppVeyor/Travis

This involves:

• Creating a new parameter for which type of CI to use, AppVeyor&Travis / Github Actions / Circle CI (future)/ Gitlab CI (future).
• Putting the correct files based on that choice
• Augmenting the README to have the badges based on that choice (does github actions even have badges?)

[rojepp]

There is some badge support, but I haven't tried it.
As for options, I don't know, I find them hard to discover and use in dotnet tools.
The admittedly few times I've used MiniScaffold I just generate and go in and delete stuff I don't want (a lot of it! 😂). I'd rather delete this one file than read up on some option.

I'm not against creating one, I just don't think anyone would care. In the same vein, there are no options for all the stuff I delete - PR/Issue templates, code coverage, generateAssemblyInfo, badges etc.