Run check-api-annotations and check-ppr on all parseable test code
check-ppr utility checks that
parse (ppr (parse s)) === parse s holds, when given a file to test.
check-api-annotations utility checks that all API annotations are actually attached to the
ParsedSource output, and that they do not precede their attachment span.
At the moment these checks are only run on a subset of code, as explicitly called for in the
These properties are supposed to hold for all GHC parseable haskell.
So rather than requiring individual developers to add specific tests to confirm their new features work properly, extend the test framework to make a pass over all the files that are expected to be parseable, and run these checks on them.