Add original hop limit to header to determine hops used (#3321)

* Set `hop_start` in header to determine how many hops each packet traveled

* Set hopLimit of response according to hops used by request

* Identify neighbors based on `hopStart` and `hopLimit`

* NeighborInfo: get all packets and assume a default broadcast interval

* Add fail-safe in case node in between is running modified firmware

* Add `viaMQTT` and `hopsAway` to NodeInfo

* Replace `HOP_RELIABLE` with hopStart for repeated packet

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

src/mesh/NodeDB.cpp

@@ -875,6 +875,12 @@ void NodeDB::updateFrom(const meshtastic_MeshPacket &mp)
 
         if (mp.rx_snr)
             info->snr = mp.rx_snr; // keep the most recent SNR we received for this node.
+
+        info->via_mqtt = mp.via_mqtt; // Store if we received this packet via MQTT
+
+        // If hopStart was set and there wasn't someone messing with the limit in the middle, add hopsAway
+        if (mp.hop_start != 0 && mp.hop_limit <= mp.hop_start)
+            info->hops_away = mp.hop_start - mp.hop_limit;
     }
 }