Different ports of the same modem may get handled by different drivers. We
therefore need to provide a list of drivers (new `Modem.Drivers' property with
signature 'as') instead of just one (removed `Modem.Driver' property with
signature 's').
$ sudo mmcli -m 0 | grep drivers
| drivers: 'qcserial, qmi_wwan'
Instead of using a predefined set of string values for 'ip-type' in
Modem.CreateBearer() and Simple.Connect(), we'll use an enumeration. The
implementation will then need to convert the requested IP family type to e.g.
the correct PDP type in 3GPP modems.
This change also consolidates the use of enums in dictionary properties when
possible to do so, as with the Rm Protocol.
Modems which end up being found unusable (e.g. no SIM, fatal SIM error, no
capabilities) will be exposed in DBus, but just with the Modem interface and
in a FAILED state which allows no actions.
Equivalent to `PinRetryCount' in the previous API. We don't have an additional
property for the retry count of the current lock, as it really is duplicating
information.
Aleksander Morgado