Should the Compilations that come out of RunFullGeneration include diagnostics automatically?

[jasonmalinowski]

See the question raised #42373 (comment) and was also raised internally.

It'd be really handy for the IDE if the Compilation that includes generated syntax trees also included the diagnostics that were generated during the generation pass; otherwise we'll have to flow it around which gets tricky, and also be responsible for incremental updates to diagnostics which isn't clear how that will work.

[jasonmalinowski]

@chsienki I think now that we have the API that gives the information directly, I wonder if we'll just be using that now always rather than taking advantage of this even if we did have it. So if you think this is good to keep around good, otherwise feel free to close if it was being kept open for our needs.