Add "Radar" funcionality to Bullet GCSS

[danarrib]

• Create a "common" MQTT Broker topic, where all aircrafts can publish AND subscribe
• Aircraft needs to broadcast it's position to this broker
• Aircraft needs to fetch other aircrafts positions and report it to INAV so it can render other aircrafts on OSD
• UI can be subscribed to this same common topic, and show other aircrafts on map

[danarrib]

INAV currently supports only 4 aircrafts on it's radar.

Suggestions on how to handle situations of more than 4 aircrafts reporting positions on the same topic are welcome.

[danarrib]

• Aircrafts must generate an unique id number (From 0 to 7)
• On conflict, aircraft should generate another number
• Only aircrafts within 9 km range will be reported to INAV
• Aircraft peers will always be ordered by it's unique ID. Aircraft A is the smallest number and aircraft H is the highest number (of aircrafts within the maximum range).
• ESP32 should estimate peers positions when not receiving data from them
• Each peers needs to report: Unique ID, Lat, Lon, Alt, Ground Speed, Vertical Speed, Ground Course