[REQ] Add support for Apache Http Client 5 Async

[jbarth]

Is your feature request related to a problem? Please describe.

The current support for java/kotlin clients with the apache-httpclient is only for synchronous clients, this request is to add support for the async client as well.

Describe the solution you'd like

An additional set of templates that will support creating the client via HttpAsyncClients.custom() and each API method will return CompletableFuture to make the calls async.

Describe alternatives you've considered

Not possible to support async apache otherwise

Additional context

[jbarth]

Suggested PR to add support: #20307