feat(header-params): Add support for header parameter extraction

[AlbRoehm]

Add functions and data classes for header parameter handling. One missing piece is how to decide weather a header parameter is required. I did not have a good idea how to extract this without adding some kind of annotation.

[tabilzad]

Thanks so much for the PR. Should be good to merge once the test is updated to cover all implementation scenarios. Let me know if you also wanna include parsing standard headers like with call.request.header(HttpHeaders.ContentLength). If not, we I can do it in a separate PR.