Caddy/FrankenPHP-based stacks

[ocdtrekkie]

It'd be worthwhile for someone to investigate new/alternative stacks using more modern server software.

@orblivion did some experimentation with Caddy in Sandstorm apps, documented here: https://github.com/sandstorm-io/sandstorm/wiki/Caddy

There is also https://frankenphp.dev/ which uses Caddy as well but replaces the php-fpm module as well.

I don't know if swapping some of these out would be slower or faster, simpler or more complicated, but it would be good for someone to test. Ideally, someone could create an alternative stack that would still work with the PHP or Python test apps, with different stacks chosen. We could always offer a lemp2 or uwsgi2 offering this way, so developers can still choose the original flavor if they prefer.