Add support of MAGE_RUN_TYPE and MAGE_RUN_CODE param to nginx

[ytorbyk]

The current approach for configuring multistore Magento requires adding some changes to a project specifically for a local environment that will be used on production as well.
In order to avoid it we can configure it in files that are not going to be used on production.

The proposed approach requires adding two files into .warden folder:

• .warden/nginx/http.conf, here you can add your rules for your domains

    map $http_host$request_uri $magento_multistore_key {
        default '';
    }

    map $http_host$uri $magento_multistore_type {
        default store;
    }

• .warden/warden-env.yml, apply the config

version: "3.5"
services:
  nginx:
    volumes:
      - ./.warden/nginx/http.conf:/etc/nginx/conf.d/http.conf