Mohammed Sadiq authored Jun 11, 2019 and Benjamin Berg committed Jul 05, 2019

This commit allows handling airplane mode for WWAN interfaces
which will be handled via rfkill and Modem Manager.

The following boolean DBUS properties are added:

* WwanAirplaneMode: read/write
* WwanHardwareAirplaneMode: read
* WwanHasAirplaneMode: read

#414