Set up GitHub Action for NuGet publishing

[ForNeVeR]

Depends on:

• [x] #51

We want to start publishing of usable artifacts to NuGet.org. For this, we'll require a right GitHub action.

See example in wpf-math.

I will have set up the actual publishing myself (with secrets and stuff), so only dotnet pack is required in this task.

Remaining tasks:

• [ ] Add THIRD-PARTY-LICENSES.txt and docs to the package
• [ ] Check the release workflow, enable NuGet publishing