WIP: Let php-fpm be used through sockets accross different containers

Hi,

I'm trying to use this image with a Nginx and after a couple of hours trying to set it up using hosts and ports (with fastcgi_pass php:9000;), it seems that using a socket might be a solution.

However, the socket file needs to be 0666.

This change will allow this:

version: '3'

services:
  web:
    image: nginx
    ports:
      - "8000:80"
    volumes:
      - ./docker/nginx/default.conf:/etc/nginx/conf.d/default.conf:ro
      - .:/app
      - "phpsocket:/run/php"
    restart: always
    working_dir: "/app"
    depends_on:
      - php
  php:
    image: fpfis/httpd-php-dev:7.4
    working_dir: /app
    volumes:
    - .:/app
    - "phpsocket:/run/php"
    environment:
      DOCUMENT_ROOT: /app/public
      XDEBUG_MODE: "coverage"
      XDEBUG_CONFIG: "remote_enable=1 remote_host=10.254.254.254 remote_port=9000 idekey=PHPSTORM remote_autostart=1"
      PHP_IDE_CONFIG: "serverName=Docker"
    healthcheck:
      interval: 10s
      timeout: 3s
      retries: 3
      start_period: 30s
    ports:
      - "9000:9000"

volumes:
    phpsocket: