Firmware should support multiple sensors (of the same type)

Commonly seen in bussed sensors such as those using SDI-12.

https://github.com/jlab-sensing/ENTS-node-firmware/issues/298

https://github.com/jlab-sensing/ENTS-node-firmware/issues/212

https://github.com/jlab-sensing/ENTS-node-firmware/issues/211