Signal quality notification %CESQ

The Nordic-proprietary %CESQ command subscribes or unsubscribes notifications of changes in signal quality.v1.0.xv1.1.xv1.2.xv1.3.x

Note: When NB-IoT system mode is used and the device is in RRC connected state, old signal quality parameter values are reported. The values are recorded and reported from the previous idle state.v1.0.xv1.1.xv1.2.x≤1v1.3.x