[#210] Fix node and service name C API

[elBoberido]

Notes for Reviewer

The node and service name C-API pretent to return a null terminated C-style string. This is not the case though, since the Rust NodeName and ServiceName is based on a Rust String and not on an iceoryx2 SemanticString.

This PR fixes the documentation and makes passing a pointer for the string length mandatory.

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

[orecham]

@elBoberido The name node_name_c_ptr causes me to scratch my head on first read. It's because it is just a pointer to chars (i.e. not null terminated)?

[orecham]

@elBoberido Maybe node_name_chars ?

[elBoberido]

Should the function then be named iox2_node_name_as_chars?

[orecham]

@elBoberido Works for me

[elBoberido]

I liked the function name since str has this implicit null-termination in the C world and chars is great for just a char array.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.95%. Comparing base (a9cc0a3) to head (3870c48).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #405      +/-   ##
==========================================
- Coverage   78.99%   78.95%   -0.04%     
==========================================
  Files         194      194              
  Lines       22730    22730              
==========================================
- Hits        17955    17946       -9     
- Misses       4775     4784       +9     

see 5 files with indirect coverage changes

[elBoberido]

We reached the Cirrus CI limit. Merging anyway since the github CI is our main CI.