[simulators.gateway] Split gateway -> utils
[simulators.gateway] Split gateway -> utils

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