Like #4232, but for keypool.

Currently, we manually append the params to the url / query string using urljoin. Instead, we can send the query params in as a dictionary

The generated client is built to work with specific version. It is fine to keep it open which versions are used in the end. But it would be much more useful to specify some versions at least as an example in the documentation here: https://guardrail.dev/scala/dropwizard/

Otherwise you leave it as an open quest for each and every developer trying to integrate it, and go through the hassle of fig