Merge branch 'develop-uedirectorysplit' into nr_initialsync

Merge branch 'nr_initialsync' of https://gitlab.eurecom.fr/oai/openairinterface5g into nr_initialsync

Conflicts:
	openair1/PHY/INIT/lte_init.c
	openair1/PHY/LTE_TRANSPORT/dci_tools.c
	openair1/PHY/LTE_TRANSPORT/ulsch_decoding.c
	openair1/PHY/LTE_UE_TRANSPORT/transport_proto_ue.h
	openair1/PHY/defs_eNB.h
	openair1/SCHED_UE/phy_procedures_lte_ue.c
	openair2/LAYER2/MAC/mac.h
	targets/RT/USER/lte-enb.c
	targets/RT/USER/lte-softmodem.h

UE directory splits, creation of UE-specific files, common UE/eNB files and extraction of UE/common components from eNodeB files. renaming of files to minimize common names across directories (i.e. defs.h, vars.h, extern.h)

Summary of changes:
- some work on better parallel processing of eNB
  try the eNB with options: --fepw --codingw
- small changes for multi-UE simulation and simulation accuracy
  (UE power levels)
- initial work for the UE to use TUN device instead of ue_ip.ko
  only done for oaisim, default bearer, compile with:
    ./build_oai --ue-nas-use-tun <rest of options>