Merge branch 'develop-SA-CBRA' of https://gitlab.eurecom.fr/oai/openairinterface5g into develop-SA-CBRA

Merge branch 'develop-SA-CBRA' of https://gitlab.eurecom.fr/oai/openairinterface5g into develop-SA-CBRA

# Conflicts:
#	cmake_targets/CMakeLists.txt
#	openair1/SIMULATION/NR_PHY/dlsim.c
#	openair1/SIMULATION/NR_PHY/ulsim.c

Merge branch 'develop-SA-CBRA' of https://gitlab.eurecom.fr/oai/openairinterface5g into develop-SA-CBRA

MR978 : 
We have incorporated 5G NR nFAPI into the develop branch
P5 and P7 interfaces for NR have been implemented. 
With this MR, downlink transmission through nFAPI will be possible. 
We have also made sure that 4G nFAPI can be used from within the develop branch.

# Conflicts:
#	openair1/PHY/NR_UE_TRANSPORT/nr_dlsch_decoding.c
#	openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c
#	openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_ulsch.c

This MR adds a multi-UE scheduler (proportional fair) for multiple UEs. Tested for two UEs, but should work for more. Additionally, it enables 12 DL slots and 2 UL slots (still fixed, will be read from the configuration file in a clean-up/follow-up MR).

* MR 1019: NASMESH: support for kernel version >= 5.6.0
he syntax for ndo_tx_timeout in Linux Kernel has changed since 5.6.0 i.e it has changed

* MR 1033: ue fixes
1. Write tx data to radio unit only on tx slots.
2. Fixed a bug in DL HARQ.
3. Disabled UE and some gNB side logs which were enabled (maybe by mistake) in previous MRs.
4. In UE, check if NDI toggled before reading SDU for PUSCH.