Add a binary_sensor or an event emitter for the status of the hubitat itself

[irvintim]

I want to monitor the health of the Hubitat from HA; if the web interface is unavailable (e.g., timeout on connection), I'd like a sensor to flip to "offline" or an "offline" event to trigger so I can send an alert (or trigger a restart). I can do this from a web monitor, but it would be nice to integrate this into this module.