Adding the NR MIB scheduler in eNB_ulsch_dlsch_scheduler, re-use LTE MAC

cmake_targets/CMakeLists.txt

nfapi/open-nFAPI/nfapi/public_inc/nfapi_nr_interface.h

openair2/GNB_APP/gnb_app.c

openair2/LAYER2/MAC/eNB_scheduler.c

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler.c

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_bch.c

openair2/LAYER2/NR_MAC_gNB/mac.h

openair2/LAYER2/NR_MAC_gNB/mac_proto.h

openair2/LAYER2/NR_MAC_gNB/main.c

openair2/RRC/NR/L2_nr_interface.c

openair2/RRC/NR/NR_L2_interface.c

openair2/RRC/NR/nr_rrc_proto.h