Add example vhost for caddy webserver

[alexander-schranz]

The caddy webserver is more and more common. Even deployer is using it in its new deployment feature where it actually will install caddy webserver and php on a blank ubuntu server when activated in deployment.

So it would be really nice to have caddy vhost which works the same as nginx: https://docs.sulu.io/en/latest/cookbook/web-server/nginx.html

Important mechanisms of the VHost

Check for static files fallback to index.php

Sulu generates thumbnails the first time they are requested, so a fallback mechanism is required. In nginx this is achieved via:

    location / {
        # try to serve file directly, fallback to index.php
        try_files $uri /index.php$is_args$args;
    }

Static files cachelifetime

Static files will have a specified cachelifetime in nginx:

   location ~* \.(?:ico|css|js|gif|webp|jpe?g|png|svg|woff|woff2|eot|ttf|mp4)$ {
        # try to serve file directly, fallback to index.php
        try_files $uri /index.php$is_args$args;
        access_log off;
        expires 1y;
        add_header Pragma public;
        add_header Cache-Control "public, immutable";
    }

This will mostly be the biggest difference to Symfony caddy configuration. Currently there is not yet any official symfony caddy vhost: symfony/symfony-docs#17471