Provide a utility to check API Annotations
At the moment it is difficult for GHC developers to know if they have broken the API Annotations.
Provide a utility that can be used as a test to show up errors in the API Annotations.
This is to be based on the current tests for ghc-api/annotations which can parse a file using the just-built GHC API, and check that no annotations are disconnected from the ParsedSource in the output.
In addition, it should be able to dump the annotations to a file, so a new feature developer can check that all changes to the parser do provide annotations.