Improve AddInitKeyword quickfix

- Extract quickfix method
- Delete redundant semicolon
- Do not replace initializer PSI element

idea/idea-analysis/src/org/jetbrains/kotlin/idea/JetBundle.properties

@@ -13,6 +13,7 @@ make.element.modifier=Make {0} {1}
 add.modifier=Add ''{0}'' modifier
 add.modifier.family=Add Modifier
 add.init.keyword=Add 'init' keyword
+add.init.keyword.family=Add 'init' keyword
 make.element.in.classifiers.open=Make ''{0}'' in {1} open
 make.class.annotation.class=Make ''{0}'' an annotation class
 make.class.annotation.class.family=Make Class an Annotation Class