Spring Add a new HttpConnector based on Java 11 HttpClient

Currently there are some HTTP connectors existed, but most of them depends on 3rd party libs, such as Apache HttpClientComponets, Reactor/Netty, OKHttp etc.

Java 11 introduced a new Reactive HttpClient based on Java 9 Flow API. It is better to add a new HTTP Connector based on this client and make it as the default HTTP client when using it in both blocking client and reactive client(eg. RestTemplate, reactive WebClient).

Comment From: bclozel

RestTemplate is now in maintenance mode, so I don't think we should change the default ClientHttpRequestFactory to using this new client implementation since it should change behavior and add no benefit without changing RestTemplate's API.

Now the WebClient connector support is already implemented and scheduled in #23432.

I'm closing this issue as a duplicate as a result.