Simplify using CBOR

[beriberikix]

CBOR is an ideal compact binary encoding format that we recommend where bits and bytes matter, like Cellular. Our Device Services already support the format. The SDK kinda supports it today but requires a fair bit of boilerplate. The ideal scenario is that the developer set a value to use CBOR and starts sending data. It would also be nice to set this globally via KConfig but still make it possible to set this at runtime.

I consider this indirectly related to #100.