Provide configuration via MQTT

[mstoffel-sag]

Is your feature request related to a problem? Please describe. For instance when I would like to know the BASE_URL of the cumulocity tenant (needed for remote connections) I have to query tedge commandline from my lib.

Describe the solution you'd like It would be great to have a MQTT topic where after I publish some empty payload get the current configuration as a json string.

[itsyitsy]

Hey Marco, good idea, we will look into this idea and check how much effort it would be to do something like this.