QML NetworkInfo API: reduce usage of monitor properties

Change affects QML NetworkInfo API.

Currently the QML-type NetworkInfo requires to set monitor properties to true to enable events from the backend and to enabled correspondent signal-handlers.

Controlling monitoring makes sense for events that occur frequently and can
increase cpu usage. This is not the case for all signals of NetworkInfo. To
simplify and ease the NetworkInfo QML API the usage of monitor-properties should be reduced.

Proposed monitor properties to be removed:
monitorNetworkInterfaceCount
monitorCurrentCellDataTechnology
monitorCellId
monitorCurrentMobileCountryCode
monitorCurrentMobileNetworkCode
monitorLocationAreaCode
Correspondent signal-handlers should be enabled by default.

Proposed monitor properties to be still kept since this information is rather dynamic and can change frequently:
monitorNetworkSignalStrength
monitorNetworkStatus
monitorNetworkName
monitorCurrentNetworkMode