F1AP encoding/decoding library

This MR provides and enc/dec library for F1AP messages. For each message the following is implemented:

• F1AP message enc/dec library
• F1 encoders according to TS 38.473
• F1 decoders according to TS 38.473
• Deep copy function
• Memory management function: manages the memory de-allocation for F1AP messages structs and struct members to prevent memory leaks and ensure optimal memory usage
• Testing: implements comprehensive tests for each F1AP message, including equality checks, to verify the correctness and integrity of all the above-mentioned functions

The new functions have been integrated in the OAI stack.

F1AP messages enc/dec libraries included in this MR:

• F1 Initial UL RRC message
• F1 DL RRC Transfer
• F1 UL RRC Message Transfer
• F1 Setup Request
• F1 Setup Response
• F1 Setup Failure
• F1 gNB-CU Configuration Update
• F1 gNB-CU Configuration Update
• F1 CU Configuration Update Acknowledge
• F1 gNB-CU Configuration Update Acknowledge
• F1AP gNB-DU Configuration Update enc/dec
• F1 DU Configuration Update Acknowledge
• F1 gNB-DU Configuration Update Acknowledge