feat: add nginx variant

[shyim]

@dallyger anything what is missing here?

[dallyger]

Seems okay, but I don't really know nginx. Thats just what was documented previously, so we used it.

The config differs from the documented configurations at https://developer.shopware.com/docs/resources/references/config-reference/server/nginx.html#nginx and https://developer.shopware.com/docs/guides/installation/requirements.html#webserver (and they themselves differ too). May be worth a look too.