Mutagen configuration at project folder

[Den4ik]

This PR provide update for mutagen that allow create custom sync config at project folder

<project_folder>/.warden/mutagen.yml

Reason

Affected MacOS
If you create local env type with .warden/warden-env.yml docker configuration like:

version: "3.5"
services:
  php-fpm:
    hostname: "${WARDEN_ENV_NAME}-php-fpm"
    image: docker.io/magenius/php-fpm:${PHP_VERSION:-7.4}${WARDEN_SVC_PHP_VARIANT:-}
    environment:
      - TRAEFIK_DOMAIN
      - TRAEFIK_SUBDOMAIN
      - COMPOSER_MEMORY_LIMIT=-1
    volumes:
      - appdata:/var/www/html
    extra_hosts:
      - ${TRAEFIK_DOMAIN}:${TRAEFIK_ADDRESS:-0.0.0.0}
      - ${TRAEFIK_SUBDOMAIN:-app}.${TRAEFIK_DOMAIN}:${TRAEFIK_ADDRESS:-0.0.0.0}

volumes:
  appdata: {}

you unable start file syncing with container.

[davidalger]

I like this a lot. Thanks! Going to include it in the next tagged release (no ETA on exactly when I'll tag it though, as I'm about ready to go on paternity leave for a couple weeks and not sure I'll have time to complete the 0.10.0 milestone before then)