Add support for first, last aggregate function parsing (#882)

* Add order by parsing to functions

* Fix doc error

* minor changes

tests/sqlparser_bigquery.rs

@@ -437,6 +437,7 @@ fn parse_map_access_offset() {
                 over: None,
                 distinct: false,
                 special: false,
+                order_by: vec![],
             })],
         })
     );