Deduplicate uniqueness prefixes

[ltrzesniewski]

I had a case where file names had duplicate uniqueness prefixes (as I described here), such as:

AssemblyToProcess.BasicTestCases.HandleExceptionBlocks.DotNet7_0.Release.DotNet7_0.received.il

Which is caused by the following code (when used with this config):

Verify/src/Verify/Verifier/InnerVerifier.cs

Lines 182 to 186 in fef7b2f

	if (namer.ResolveUniqueForRuntimeAndVersion() ||
	TargetAssembly.TargetsMultipleFramework)
	{
	sharedUniqueness.Add(Namer.RuntimeAndVersion);
	}

This proposed fix makes sure the prefixes are distinct.

I'm not sure why the received ans verified file prefixes aren't necessarily equal, but this seems to confuse the tools I use.