Fix: #5669 online validator badge (#5909)

* fix: enable online validator badge

since online validator badge now can handle OAS3 specs

src/core/plugins/oas3/wrap-components/online-validator-badge.js

 import { OAS3ComponentWrapFactory } from "../helpers"
+import OnlineValidatorBadge from "core/components/online-validator-badge"
 
-// We're disabling the Online Validator Badge until the online validator
-// can handle OAS3 specs.
-export default OAS3ComponentWrapFactory(() => null)
+// OAS3 spec is now supported by the online validator.
+export default OAS3ComponentWrapFactory(OnlineValidatorBadge)