Add parent and field name to depreciation validation error

[eskimoblood]

I try to use the validate function to log if a query with deprecated fields was called. While it works and I get an error back, the information which field causes the error is unfortunately not part of the GraphQLError object. As it looks like the GraphQLError constructor allows to pass a path or an extensions object that could hold this information would it make sense to add this information to the error as well?