[Story] Improve routerConfig device twin format

[bastbu]

Description

The router_config message specified by the LNS protocol has a couple of inconsistencies that are not always intuitive. With respect to casing, sometimes pascal case and sometimes snake case is used. The formats (tuples as nested arrays) of some properties are not as restrictive as they could be. We should homogenize the router configuration format that we require to be present in the desired twin properties of the station.

Acceptance criteria

• [ ] routerConfig structure in device twin is consistent
• [ ] routerConfig structure of device twin is documented
• [ ] quickstart template deploys a station device with the correct config to IoT hub

[roel4ez]

@mandur this has no parent, should this be under #344 ?