Setup GitHub Actions artifact packaging

[Washi1337]

The csproj files create *.nupkg files that can be uploaded and/or pushed to nuget.

[kfrajtak]

Completing this task will be very much appreciated :)

[Washi1337]

One of the problems with pushing to nuget is that there already exists a project called Echo on nuget. We might need to consider a name change, or add some kind of a prefix namespace.

[sunnamed434]

Any ideas? I think EchoFramework sounds good, like EntityFramework