MMIfaceModem handlers always connected
Always connect all method handlers, even in failed state, so that the returned error is much more descriptive. E.g. instead of this:
$ sudo mmcli -m 0 -e
error: couldn't enable the modem: 'GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: Method Enable is not implemented
on interface org.freedesktop.ModemManager1.Modem'
We'll get this:
$ sudo mmcli -m 0 -e
error: couldn't enable the modem: 'GDBus.Error:org.freedesktop.ModemManager1.Error.Core.WrongState: modem in failed state'
The MR also includes an additional fix to avoid redundant logic related to SIM hot swap management.