RFC: Bring zcbor as CBOR decoder/encoder in replacement for TinyCBOR

[de-nordic]

Origin

zcbor https://github.com/NordicSemiconductor/zcbor

Purpose

In replacement of the current heavily-modified TinyCBOR fork we use as a CBOR encoder/decoder.
zcbor is a light CBOR encoder/decoder with, optional, capability of generating decoding code from CDDL descriptions of data structures.
Our TinyCBOR fork will then be deprecated and removed in time.

Mode of integration

As a module: it is easier to maintain and update with patches from the origin.
Module path would be modules/lib/zcbor

Pull Request

** THIS IS WORK IN PROGRESS **
The zcbor module Kconfig and cmake recipe:
#43332

Description

Currently the only user of CBOR encoder/decoder within Zephyr is mcumgr. The encoder we use is custom version of TinyCBOR.
Complete discussion on TinyCBOR replacement, on what are possible alternatives and reasons is present here #40591

In general we are trying to replace hard to update non vanilla fork of TinyCBOR with lightweight, simpler and easier to maintain variant zcbor.

Dependencies

This is standalone project and depends only on C compiler.
Additional and optional feature of auto generating decoding source is dependent on python interpreter.

Revision

The newest commit on main:
NordicSemiconductor/zcbor@942ae07

License

As stated here: https://github.com/NordicSemiconductor/zcbor/blob/main/LICENSE
is Apache v2.

[carlescufi]

Approved by the TSC

[carlescufi]

This is now complete.