Merge remote-tracking branch 'origin/rrc-qos-refactor' into integration_2026_w07 (!3907)

RRC QoS refactor: PDU Session Modify support, SDAP fixes, and code improvements

The goal of this MR is to prepare the RRC/NGAP layer for the multi-QoS
support. The MR:

- enables PDU Session Resource Modify support in RRC/NGAP/E1AP
- fixes SDAP header mapping
- enables SDAP by default
- refactors QoS flow handling in RRC/NGAP
- improves error handling, and code maintainability in RRC/NGAP

Changes:

- NGAP PDU Session Modify:
  * add NGAP PDU Session Resource Modify Request/Response handling with
    proper error reporting for unrecognized sessions and AMF UE NGAP ID
    validation
- E1AP Bearer Context Modification:
  * add DRB To Remove List IE to support DRB release during modify
  * rename numQosFlow2Setup to numQosFlowsMod in DRB To Modify List
- RRC QoS flow handling:
  * enable multi-QoS flow support per DRB
  * add utilities to map NGAP QoS parameters to E1AP
  * filter QoS flows by DRB ID
- SDAP configuration:
  * Fix SDAP header UL/DL mapping between internal representation and
    ASN.1 enum (invert mapping)
  * change SDAP header fields from long to bool for clarity
- F1 DRB setup refactoring:
  * Extract shared helpers for F1 DRB setup list filling
  * reduce duplication between E1 response and direct DRB setup paths
- AMBR management:
  * Store AMBR in UE context
  * validate AMBR is set before bearer setup
- Configuration:
  * remove unused drbs configuration parameter
  * enable SDAP by default (change default from false to true)

ci-scripts/conf_files/gnb.sa.band66.106prb.rfsim.conf

@@ -18,7 +18,7 @@ gNBs =
     ////////// Physical parameters:
 
     min_rxtxtime                                              = 6;
-    enable_sdap = 1;
+    enable_sdap = 0;
 
     servingCellConfigCommon = (
     {

ci-scripts/conf_files/untested/gnb.sa.band66.fr1.106PRB.usrpn300.conf

@@ -18,7 +18,7 @@ gNBs =
     ////////// Physical parameters:
 
     min_rxtxtime                                              = 6;
-    enable_sdap = 1;
+    enable_sdap = 0;
 
     servingCellConfigCommon = (
     {