Fixes for Initial UE Context Setup
This MR fixes DRB aggregation from E1 so DRBs from multiple PDU sessions
are appended correctly into the F1 DRB array instead of overwriting
existing entries. It also makes NGAP Initial Context Setup skip PDU
sessions that are already established for the UE, only setting up new
sessions.
DRB aggregation from E1: Adjust fill_drb_to_be_setup_from_e1_resp to
pass &drbs[nb_drb] into fill_f1_drbs_from_e1, ensuring DRBs from later
PDU sessions are appended after the current count.
Duplicate PDU sessions in NGAP Initial Context Setup: In
rrc_gNB_process_NGAP_INITIAL_CONTEXT_SETUP_REQ, detect requested PDU
session IDs that already exist with PDU_SESSION_STATUS_ESTABLISHED, log
a warning, and skip them so they are not added to UE->initial_pdus.
Robert Schmidt
4f7cd88e4c