Add ability to see and control power production status in envoy integration

When logged into the web interface of my envoy as an installer (using password provided via Default Installer Password Calculation for Envoy), I am able to switch power production of my installation on or off and see the current status (on by default). It would be great to have this option using the integration so I can create an automation to switch off power production during hours when my energy provider has a negative dynamic price per KWh and my consumption is lower than the output of my solar system. During those times, my solar system actually costs me money so it makes sense to turn it off.