refactor: improve error messages

Author: Rel1cx

packages/plugins/eslint-plugin-react-x/src/rules/jsx-no-undef.ts

@@ -20,7 +20,7 @@ export default createRule<[], MessageID>({
       [Symbol.for("rule_features")]: RULE_FEATURES,
     },
     messages: {
-      jsxNoUndef: "JSX variable {{name}} is not defined.",
+      jsxNoUndef: "JSX variable '{{name}}' is not defined.",
     },
     schema: [],
   },