Initialize F1AP

modify some issues
add f1ap ue context procedure

add DU_handle_DL_NR_RRC_MESSAGE_TRANSFER

 Conflicts:
	common/utils/ocp_itti/intertask_interface.h
	openair2/COMMON/gtpv1_u_messages_types.h
	openair2/GNB_APP/gnb_config.c
	openair2/RRC/NR/MESSAGES/asn1_msg.c
	openair2/RRC/NR/nr_rrc_proto.h
	openair2/RRC/NR/rrc_gNB.c
	openair2/RRC/NR/rrc_gNB_NGAP.c
	openair2/RRC/NR_UE/rrc_UE.c
	openair3/NAS/NR_UE/nr_nas_msg_sim.h
	openair3/NGAP/ngap_gNB_nas_procedures.c

 Conflicts:
	common/utils/ocp_itti/intertask_interface.h
	openair2/RRC/NR/rrc_gNB.c
	openair2/RRC/NR/rrc_gNB_NGAP.c
	openair2/RRC/NR_UE/rrc_UE.c
	openair2/RRC/NR_UE/rrc_defs.h
	openair3/NGAP/ngap_gNB_nas_procedures.c

MR932 : Nr sa ngap rrc wk42 
- Initial implementation of NGAP and RRC extensions for SA
 
MR956 : Correct use of ssb_position bitmaps  

MR958 : 5G NR Downlink DMRS Type 2
- Implementation of 5G NR Downlink DMRS type 2 (generation on gNB side, channel estimation with linear interpolation in frequency domain on UE side), needed for MIMO
  
MR961 : 5G NR UE TTI cleanup  
- Remove current_thread_id array, nr_tti_rx, nr_tti_tx, subframe_rx and subframe_tx

MR965 : fix a segdev

Conflicts:
	openair1/PHY/NR_UE_TRANSPORT/dci_nr.c
	openair1/PHY/NR_UE_TRANSPORT/nr_transport_proto_ue.h
	openair1/SCHED_NR_UE/phy_procedures_nr_ue.c

MR939 : Nr rlc am bugfix w44 
- bugfix

MR948 : nr: rlc: hotfix - forgot to store frame and subfram  
- minor bugfix

MR942 : Feature/make s1 mme port configurable 
- This patch adds an optional "port" option to set another sctp port than 36412 

MR959 : minor: remove a CPPCHECK error for NR RLC
- remove a CPPCHECK error (not a real error) for NR RLC

Merge remote-tracking branch 'origin/hotfix-minor-remove-nr-rlc-cppcheck-error' into integration_2020_wk47

Merge remote-tracking branch 'origin/feature/make-s1-mme-port-configurable' into integration_2020_wk47

Add rrc_gNB_send_NGAP_PDUSESSION_SETUP_RESP
Fix some problems about pdu session setup