.NET: Thin 3.0: Ensure AOT compatibility

Ensure that Ignite.NET library is AOT-compatible: https://devblogs.microsoft.com/dotnet/creating-aot-compatible-libraries/

To test this:

• Run existing tests in AOT mode? Not sure if NUnit can do that.
• Write separate tests to check basic functionality for AOT
• See https://devblogs.microsoft.com/dotnet/testing-your-native-aot-dotnet-apps/ (note: experimental, closed-source testing framework)