Allow to exclude assemblies from including RoslynAnalyzers in them.

[SolidAlloy]

Currently, RoslynAnalyzers is referenced in every project generated by Unity. When I add a package or asset that has code in its own assembly, Unity generates a project for it and RoslynAnalyzers gets referenced there. It produces a lot of warnings that are not relevant to me as I don't plan to change code in the packages I am using.

It would be helpful if it was possible to exclude certain assemblies so that RoslynAnalyzers is not referenced in the projects generated with those assemblies. This way, RoslynAnalyzers could produce warnings only for the code I own.