Feature request: check if numbers of warnings increase in CI

[oharboe]

          > @maliberty I seem to recall you added number of warnings and errors to the `make metadata` information?

Does this mean that if there is a regression(increase) in number of warnings that this will now be caught by CI and that a choice can be made whether or not to accept the new warnings?

It means only that it is recorded currently. We could need to set limits to check against. It seems unrelated to this PR though

Originally posted by @maliberty in The-OpenROAD-Project/OpenROAD#4889 (comment)