AssertionError executing authz stmt on UDF without keyspace

Performing a GRANT or REVOKE on a user defined function requires the function name to be qualified by its keyspace. Unlike GRANT/REVOKE on a table, the keyspace cannot be inferred from the ClientState as it's needed by the parser to either lookup the function (in 2.2), or convert the function arguments from CQL types to their corresponding AbstractType (in 3.0+).

Currently, performing such a statement results in an unhandled assert error and a ServerError response to the client.