ms-basic-connect-extensions: implement 'Device Slot Mappings'

We set device slot mappings and we can see the following information.

mimcli -d /dev/cdc-wdm0 -p --ms-set-device-slot-mappings=1
[/dev/cdc-wdm0] Updated slot mappings retrieved:
            Executor 0: slot 1

We query device slot mappings and we can see the following information.

mbimcli -d /dev/cdc-wdm0 -p --ms-query-device-slot-mappings
[/dev/cdc-wdm0] Slot mappings retrieved:
            Executor 0: slot 0