refactor: new dev/prod containers

- Use a single Dockerfile for all Zeppelin services
- Add a Dockerfile in project root that can be used by
  app hosting services
- Provide a standalone and lightweight prod setup
  - Standalone is the same as the old setup, with mysql+nginx
  - Lightweight only runs bot+backend+dash, no mysql/nginx
- Remove mounted mysql data folders for dev and prod
  - This resolves permission issues caused by the mount
  - The mysql service uses a regular named volume now
- Simplify .env options and clearly separate different prod setups
- Remove update.sh
  - Different setups require different update procedures, so a common
    update.sh no longer works

.devcontainer/devcontainer.json

@@ -5,5 +5,5 @@
 
   "service": "devenv",
   "remoteUser": "ubuntu",
-  "workspaceFolder": "/home/ubuntu/zeppelin"
+  "workspaceFolder": "/workspace/zeppelin"
 }