check-code: drop the camelcase checks Fro about 2 years we have been using CamelCase is class names. That rules gets in the way of assigning class or exception in compatibility layers. I think it is safe to drop it now that we started using CamelCase for some case. My motivation for this is the need to assign `FileNotFoundError` in `pycompat`. Differential Revision: https://phab.mercurial-scm.org/D11309