debug: CTF Tracing with POSIX backend

This commit implements a CTF-backend for Zephyr's tracing API.
The CTF-backend itself is split in a middle-layer and a bottom-layer.
- Middle-layer decides the payload in event transactions,
- Bottom-layer implements the IO transport.

A simple POSIX bottom-layer is provided so far.

Signed-off-by: François Delawarde <fnde@oticon.com>
16 files changed