Generate message types for TypeScript, protobuf, ...

[coderbyheart]

Many projects in the nRF Asset Tracker need to verify incoming messages and need TypeScript definitions when building outgoing messages to ensure data that is passed around follows the cloud protocol.

Right now each project (web app, cloud backend, ...) has their own implementation, but we keep adding places where this is repeated. This creates code duplication that must be kept in sync with changes to the cloud protocol, and these happen quite often.

Therefore:

• create a repo of automatically generated TypeScript types and a JSON schema validator based on the definitions in the docs repository. Follow the example from https://github.com/NordicSemiconductor/lwm2m-types-js for generating TypeScript types. Publish to NPM.
• add the generation of protobuf message encoders and decoders for TypeScript and embedded C (using nanopb). No prior work exists here, so this needs some research.