feat: nginx port, cors configuration, required variables, default value for mysql database

[shpran]

Changes

• New NGINX_PORT environment variable, which allow using HTTP connection
• Added default value for MYSQL_DATABASE environment variable
• Most of the variables are required to compose - an error will be thrown if some of them are empty or omitted
• appstream nginx template removed - php:9000 pass will be used directly
• app nginx template sue new configuration:
  • Listen 80 port
  • Proxy configuration
  • CORS