[enhancement] making `HttpClientRequest` implement `Cloneable` interface

[mechite]

This is my use case: sirius.stellar.esthree
I am currently trying to use HttpClientRequest in the DEsthreePaginator#nextResponse method
— I want to clone the request builder.

Here is another example of how that should look:

HttpClientRequest request = client.request();
request.url(...);

// copy one
final var requestA = request;
requestA.queryParam("sentry-man", "yes");
var responseA = requestA.GET();

// copy two
final var requestB = request;
requestB.queryParam("using-avaje", "yes");
var responseB = requestB.GET();

...where right now, requestA and requestB are still referencing the original.
I want to throw a half-built HttpClientRequest around my application.

Being able to do HttpClientRequest#clone() would be nice.