[#210] Add proc macro for FFI boilerplate code

[elBoberido]

Notes for Reviewer

This PR adds a proc macro to reduce the amount of boilerplate code required for the FFI crate

Pre-Review Checklist for the PR Author

1. Add sensible notes for the reviewer
2. PR title is short, expressive and meaningful
3. Relevant issues are linked in the References section
4. Every source code file has a copyright header with SPDX-License-Identifier: Apache-2.0 OR MIT
5. Branch follows the naming format (iox2-123-introduce-posix-ipc-example)
6. Commits messages are according to this guideline
   • Commit messages have the issue ID ([#123] Add posix ipc example)
   • Commit author matches Eclipse Contributor Agreement (and ECA is signed)
7. Tests follow the best practice for testing
8. Changelog updated in the unreleased section including API breaking changes
9. Assign PR to reviewer
10. All checks have passed (except task-list-completed)

Checklist for the PR Reviewer

• Commits are properly organized and messages are according to the guideline
• Unit tests have been written for new behavior
• Public API is documented
• PR title describes the changes

Post-review Checklist for the PR Author

1. All open points are addressed and tracked via issues

References

Relates to #210

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.34%. Comparing base (036de1e) to head (b66aec7).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #295      +/-   ##
==========================================
- Coverage   80.38%   80.34%   -0.04%     
==========================================
  Files         191      191              
  Lines       21814    21814              
==========================================
- Hits        17535    17527       -8     
- Misses       4279     4287       +8     

see 5 files with indirect coverage changes