Changing current allowed/preferred modes requires the device to be in low-power
mode, so we will make sure we return an error if any power operation is already
ongoing when a new one is requested.
AT+URAT=? provides the format expected, but looks like it isn't implemented
differently for the different u-blox devices seen, so we need an additional
level of filtering which currently is applied per device model string.
A default implementation to monitor the ongoing connection is provided in the
generic MMBroadbandModem, based on AT+CGACT? to check whether the PDP context
of the connection (identified by the cached cid) is active or not.
This commit also disables the connection monitoring logic in those plugins that
have custom connection methods.
Aleksander Morgado