XNAP: Add encode/decode and unit tests for Xn Setup Request/Response/Failure
This MR adds complete support for the following in accordance with
3GPP TS 38.423 v16.2.0
- Add Xn Setup Request, Response, and Failure message type definitions
- Implement ASN.1 encode/decode for all Xn Setup messages
- Add equality checks and memory management helpers
- Create XNAP unit test infrastructure
Co-author: @venkatareddy
Acknowledgement
This work was carried out as part of research and development at Indian
Institute of Science (IISc), Bengaluru.