xenomai port

## Brief feature description

porting to xenomai (www.xenomai.org)
## Detailed information

Hi, I may try to port it and evaluate it to the realtime xenomai native api.

Before, I have few questions about the api.
I understand data is shared among memory shared segments, no problem.

Porting would imply to use xenomai native heaps.
I will need to know if it is using a static size memory segment or dynamic allocation.
In my case memory segments must be allocated at startup time and no more modified during life of process

Synchronisation access to shared memory segments :
What are the mechanisms used to synchronise tasks and memory access ?
I suppose it is protected by mutex or some semaphore mechanisms, these mechanisms would need being implemented using xenomai native api too.

congestion:
It is probable that producer is really faster than consumers, is there a way to estimate measure congestion ?

Porting to realtime xenomai would imply avoid any system calls like file/pipe access or network access. is it ok ?

The issue names no files, tests, or entry points. Start by reviewing the Xenomai native API and iceoryx's handling of shared-memory allocation, synchronization, congestion, and system access. Before implementation, define the supported porting scope and the answers to the listed compatibility questions.

Written by the indexing model from the issue text.