Unify filtering of unnecessary analyzer nodes with the Roslyn logic

For the legacy project system, Roslyn has logic to avoid showing analyzer nodes in certain cases to keep the list smaller. In our CPS project system, these nodes are made by this code in this repo but there is no equivalent filtering.

The current Roslyn code (warning: it's being tweaked a bit for generators) is visible here: https://github.com/dotnet/roslyn/blob/d8eb54d3c56f3b8415eb713b94759bce085e13c7/src/VisualStudio/Core/Impl/SolutionExplorer/AnalyzerItem/AnalyzerItemSource.cs#L209