Handle image cache resolve on Nginx side

[lecajer]

Simplify usage for client that should not take care of image cache state. A common usecase is when a Storefront consume Sylius API

In image cache is missing, NginX will call Sylius with /resolve and then serve the image to the client.

Whitout this:

GET /media/cache/image/xx/yy.img.jpg 404

Then client has to do

GET /media/cache/image/resolve/xx/yy.img.jpg 302 (or 404)
GET /media/cache/image/xx/yy.img.jpg 200

With this change

GET /media/cache/image/xx/yy.img.jpg 200 (or 404)

NginX takes care of checking if the cache exists and generate it if not.