[E2 agent] Move UE RRC_CONNECTED state signaling

E2SM UE ID requires GUAMI info which is unknown when the RRC connection is established.

GUAMI is extracted from Initial Context Setup Request sent from AMF.

Previous state:

(gdb) p *gnb $2 = {amf_ue_ngap_id = 0, guami = {plmn_id = {mcc = 0, mnc = 0, mnc_digit_len = 3 '\003'}, amf_region_id = 0 '\000', amf_set_id = 0, amf_ptr = 0}, gnb_cu_ue_f1ap_lst_len = 0, gnb_cu_ue_f1ap_lst = 0x0, gnb_cu_cp_ue_e1ap_lst_len = 0, gnb_cu_cp_ue_e1ap_lst = 0x0, ran_ue_id = 0x7ffff0005110, ng_ran_node_ue_xnap_id = 0x0, global_gnb_id = 0x0, global_ng_ran_node_id = 0x0}

Current state:

(gdb) p *gnb $1 = {amf_ue_ngap_id = 2, guami = {plmn_id = {mcc = 208, mnc = 99, mnc_digit_len = 2 '\002'}, amf_region_id = 1 '\001', amf_set_id = 1, amf_ptr = 1}, gnb_cu_ue_f1ap_lst_len = 0, gnb_cu_ue_f1ap_lst = 0x0, gnb_cu_cp_ue_e1ap_lst_len = 0, gnb_cu_cp_ue_e1ap_lst = 0x0, ran_ue_id = 0x7ffff0005110, ng_ran_node_ue_xnap_id = 0x0, global_gnb_id = 0x0, global_ng_ran_node_id = 0x0}