Make the SDK usable from NuGet (HAST-175)

[Piedone]

Instead of having to start with the SDK solution create NuGet packages that you'll then be able to add to your app.

• Let's use our NuGet-publishing GitHub workflow if possible.
• Remove the note from WorkingWithHastlayer.
• Add a NuGetTest solution that runs the verification tests with the NuGet packages.
• Hardware Frameworks need to be packaged as well, and then used as plain files somehow.
• Is it better to create a different solution just for NuGet publishing, without a lot of the sample and test projects, or make affected projects <IsPackagable>false</IsPackagable> (publish-nuget can already ignore such projects without erroring out)?
• Figure out something for Lombiq.Arithmetics and Hast.Vitis.HardwareFramework. These most possibly need their own NuGet publish workflows. Publish them first.
• Add NuGet-referencing verbiage to Hastlayer.cs:
  • "Did you install the necessary NuGet package for the given device?" for "There is no supported device..."
  • "Did you install the necessary NuGet package for the given device?" for "No suitable hardware implementation..." (device support packages should already depend on the necessary composer packages, hence the same text).
• Should we package up Hast.Console, perhaps as a .NET Tool? - This doesn't make much sense, no.

Prerequisite: #34

Jira issue