Centralizes 5G-S-TMSI bit manipulation logic for consistency and
maintainability. All manual bit operations replaced with documented
helper functions following TS 23.003 bit layout specification.
- Add helper functions for 5G-S-TMSI operations:
* nr_construct_5g_s_tmsi_part1: 5G-S-TMSI construction is defined
in 3GPP TS 23.003 and relevant at both gNB and UE side
* Add helper functions to be later used in NG Paging
* Adopt in NAS UE
* nr_extract_5g_s_tmsi_part1() - extract Part1 (39 bits) from full
* nr_extract_5g_s_tmsi_part2() - extract Part2 (9 bits) from full
* nr_build_full_5g_s_tmsi() - reconstruct full from Part1+Part2
* nr_deconstruct_5g_s_tmsi() - deconstruct into components
- Refactor manual bit manipulation to use helper functions:
* asn1_msg.c: use nr_extract_5g_s_tmsi_part1() in RRCSetupRequest
* asn1_msg.c: use nr_extract_5g_s_tmsi_part2() in RRCSetupComplete
* rrc_gNB.c: use nr_build_full_5g_s_tmsi() when reconstructing from parts
* rrc_gNB.c: use nr_deconstruct_5g_s_tmsi() when extracting components
- Optimize nr_construct_5g_s_tmsi_part1() to reuse extract function