Wart: Http4s Server - Remove parameters where they are not needed

[amarrella]

Since #382 , routes are being generated with unused parameters and this causes several warnings.

I think we should at least ignore them (or ignore the warning with @_ if they are in the path.

(I would like a lot to use apibuilder with https://github.com/sirocchj/sbt-api-builder and -Xfatal-warnings enabled, but this and #398 don't allow me to do that :( )

[amarrella]

Forgot to add a detail: I'm using the tpolecat flags and the flag that generates this warning is -Ywarn-unused:patvars