[simulators.gateway] Split gateway file
[simulators.gateway] Split gateway file

jvanmalder/ttn,LoRaWanSoFa/ttn,LoRaWanSoFa/ttn,mgranberry/ttn,jvanmalder/ttn,mgranberry/ttn,TheThingsNetwork/ttn,mgranberry/ttn,TheThingsNetwork/ttn,TheThingsNetwork/ttn,jvanmalder/ttn