src: refactor callback #defines into C++ templates

Use template helpers instead of `#define`s to generate
the raw C callbacks that are passed to the HTTP parser library.

A nice effect of this is that it is more obvious what
parameters the `Parser` methods take.

PR-URL: https://github.com/nodejs/node/pull/18133


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>