implement header parsing within frameworks

[bblfish]

Currently tests are run in Akka on hand built versions of the example code, and we have something a bit more programmatic with http4s. This is useful to get the framework going.

The problem is that those tests don't tell us how headers are rally parsed by the underlying systems, and that is quite important if we want to know if our signatures are going to work correctly when deployed.

For example does the request

POST /path?param=value&foo=bar&baz=bat%2Dman HTTP/1.1
Host: www.example.com

create a modelled object where the %2D has been decoded or not? Depending
on that the result of using @query may be different. Other examples are bound to exist.

Akka has tests suites that allow one to do this (but don't use munit).
Http4s may be more complicated as it abstracts over a number of underlying components.