Finish off basic dynamic node

wit/dynamic_node.wit

@@ -21,17 +21,11 @@ interface types {
         read-into-string: func() -> string;
     }
 
-    resource write-map {
-        keys: func() -> list<string>;
-        put: func(name: string, value: string);
-    }
-
     resource csv-readers {
         get-reader: func(name: string) -> option<csv-reader>;
     }
 
     resource csv-writer {
-        write-map: func(row: write-map);
         write-row: func(row: list<tuple<string, string>>);
     }