C++: Support MaD alert provenance

[geoffw0]

Extends the work on #15501 to fully include CPP.

@aschackmull please could you check I haven't left anything out.

[aschackmull]

LGTM. A few other languages that also have support for QL-defined csv rows use "SourceModelCsv", "SinkModelCsv", and "SummaryModelCsv" to get some provenance for those models as well, so you may want that as opposed to model = "". On the other hand, if you don't have too many QL-defined csv models, then the better option might just be to do a bit of follow-up work that converts them to yml and then deprecate the csv extension points, as that's really just legacy from before we had yml-based extensions.

[geoffw0]

if you don't have too many QL-defined csv models, then the better option might just be to do a bit of follow-up work that converts them to yml and then deprecate the csv extension points, as that's really just legacy from before we had yml-based extensions.

I think that accurately describes the situation in CPP - MaD was only added recently and there are just a couple of QL-based, non-test CSV extension points. I'll create an issue to migrate them to .YML and deprecate the classes.