Add device profile example with consumable capacity

[sunya-ch]

Implement the device profile introduced in #129 for an example of consumable capacity.

This would help demonstrate how the feature can be implemented in the driver and make it easier to gather feedback for its future improvements.

I’m happy to contribute by adding a simple network device profile with consumable bandwidth as a concrete example, but I’m not sure whether this work should wait until #91
is concluded.

[pohly]

/assign @sunya-ch