Add "name" to @GraphQLArg decorator

[tigloo]

I need to build an API that uses query parameter names which clash with reserved words in Dart, such as "class" or "extension". Due to this, I need to choose an alternative parameter name when declaring the query function but would like to remap it to the original argument name from the GraphQL spec.

Example:

@Query(name: "AccountList") Function<Account?> accountList( @GraphQLArg(name: "class") String? class_ ) {...}