Feed to two MeshCore packet analyzer MQTT servers at the same time

[rinchen]

There is some interest in extending the MeshCore MQTT subsystem to feed two packet analyzers at the same time: a local one and Meshmapper (aka letsmesh). This could work because those systems are publish-only.

• We'd have to refactor the connection panel to allow for multiple connections
• We'd have to ensure the MeshCore MQTT implementation can handle multiple connections at the same time. Today it's designed for a single one
• We'd have to rethink how to display the status in the main panel.

It's a fair amount of work, especially if we don't want to diverge too dramatically from the common UI/UX between Meshtastic and MeshCore.

[rinchen]

For Colorado specifically, we want to feed our own MC MQTT as well as MeshMapper.