Potential `[ObsoleteAttribute]` Issue

[JasonBock]

To reproduce:

var code =
	"""
	using Rocks;
	using System;

	#nullable enable

	namespace MockTests
	{
		[Obsolete("This interface is not intended to be used directly by user code")]
		public interface IShader
		{
			[Obsolete("This method is not intended to be used directly by user code")]
			uint GetPixelOptions();
		}

		public interface IPixelShader : IShader
		{
			void Execute();
		}

		public static class Test
		{
			public static void Generate()
			{
				var rock = Rock.Create<IPixelShader>();
			}
		}
	}
	""";

In the test project, because I think generalDiagnosticOption: ReportDiagnostic.Error is not set like it is in the code gen test app, this doesn't fail, but it will when warnings are errors, something like this:

error CS0618: 'ID2D1InputDescriptionsLoader' is obsolete: 'This interface is not intended to be used directly by user code'

This was found on ComputeSharp.D2D1.ID2D1PixelShader