Make the containerized app production-ready

[ttulka]

In order to use the containerized simulator, we need to decouple the web UI from the simulator itself.

Changes:

• Console abstraction to allow the simulator to run without the web UI to be initialized (WebSocket events are sent only when the web runs)
• config.json - AutoStart flag to start the simulator with provided configurations right away with no need to open the web and start it manually
• device and gtw configs are parametrized only for the case they run as a container (default templates in /docker dir) - one can set up the desired behavior just via env vars or the container
• Prometheus metrics - to analyze the simulator in production environments
• Option to setup a Base64-encoded payload
• Minor fixes

None of these changes are breaking ones, the default config is set up so that everything works as previously.

[ttulka]

Hey @fedyfausto Have you got some time to check this PR? I think the improvements are quite useful for a lot of users. Thanks!