create a docker dedicated .env file

[techws-dev]

There are many environment variables in this project specific to environment configuration in compose files.

It could be great to make a docker.env.default file default options, and add env_file option to compose.yaml (under php service):

env_file:
  - path: ./docker.env
    required: false

There could be some benefits:

• separate project environment from infrastructure environment
• group options in one file
• not pollute Symfony project .env files

With the same idea DATABASE_URL could be removed from compose.yaml, because it's defined in Symfony env files (and in docker-entrypoint.sh it's already checked on the .env file)