UE/ESM: move _esm_ebr_data to nas_user_t

openair3/NAS/UE/ESM/DedicatedEpsBearerContextActivation.c

openair3/NAS/UE/ESM/DefaultEpsBearerContextActivation.c

openair3/NAS/UE/ESM/EpsBearerContextDeactivation.c

openair3/NAS/UE/ESM/SAP/esm_recv.c

openair3/NAS/UE/ESM/esm_ebr.c

openair3/NAS/UE/ESM/esm_ebr.h

openair3/NAS/UE/ESM/esm_ebr_context.c

openair3/NAS/UE/ESM/esm_main.c

openair3/NAS/UE/ESM/esm_main.h

openair3/NAS/UE/nas_proc.c

openair3/NAS/UE/nas_proc.h

openair3/NAS/UE/nas_user.c

openair3/NAS/UE/user_defs.h