Optimize Docker (#575)

* reduce docker dev size

* reduce docker prod size

* fix lint

* add gunicorn

* fix bandit reported issues

* add docs external link icon

* add env vars to docs

* add permission to docker

* merge to one backend Dockerfile

* fix codefactor issues

* add docs for puid/pgid

* add docker healthcheck

docker-compose.dev.yml

@@ -23,7 +23,8 @@ services:
     image: mealie-api:dev
     build:
       context: ./
-      dockerfile: Dockerfile.dev
+      target: development
+      dockerfile: Dockerfile
     restart: always
     ports:
       - 9921:9000