Off-chain PoC witnesses and beacon analysis

[steakneedy]

A new miner image (2022.12.13.0 GA) was released, activating off-chain PoC witnesses and beacons for testing.
Before switching to SOL, it could be interesting to include these as an additional feature in the script already.

Some example log entries:

Beaconing
[ gateway-rs ] transmitting beacon, beacon: xxxxx ==, module: beacon

Witnessing
[ gateway-rs ] poc witness report submitted, beacon: xxxxx ==, module: beacon

I am unsure though if those are off-chain PoC witnesses or whether they may possibly be other LoRa packets.