Add flaky test for inferred length in doc string

The parameter used for inferring the length is not deterministic because of the non-determinism of hash set. This leads to changing logic between builds, shown by this flaky test.

Author: delreluca

MKL.NET.WrapperGenerator.Tests/GeneratorTest.cs

@@ -49,7 +49,10 @@ public static unsafe extern void dummy(int M, int N,
 
         generatorResult.Generator.Should().BeSameAs(generator);
         generatorResult.Diagnostics.Should().BeEmpty();
-        generatorResult.GeneratedSources.Should().HaveCount(1);
+        generatorResult.GeneratedSources.Should().ContainSingle()
+            .Which.SourceText.ToString().Should().Contain(
+                "///<remarks>" +
+                "This version infers the length parameter <c>N</c> from <paramref name=\"A\" />'s length.</remarks>");
         generatorResult.Exception.Should().BeNull();
     }