Add ANTLR grammar rules for 'bye' and 'goodbye' with parser and listener updates

Week_3/week3.g4

@@ -3,3 +3,4 @@ grammar week3;
 start : 'minimal' ID ;
 ID : [a-zA-Z]+ ;
 WS : [ \t\r\n]+ -> skip ;
+bye : ('bye'| 'goodbye') ID ;