Checks.isJavaIdentifier doesn't handle corner case such as "p.1q". We need to replace this with a better method to check module, package, and type names.

In addition, we need to re-check the module-info.class readers to make sure that they do the correct validation (as validation is not strict when reading from a .class file). In particular, an unqualified cannot contain '.'. ';' and '[' (if there is a '/' then it gets translated to '.' as part of translation from internal to binary form).