Merge branch 'nr_pbch' into develop-nr

cmake_targets/CMakeLists.txt

openair1/PHY/INIT/nr_init_ue.c

openair1/PHY/INIT/nr_parms.c

openair1/PHY/NR_REFSIG/nr_dmrs_rx.c

openair1/PHY/NR_UE_ESTIMATION/nr_dl_channel_estimation.c

openair1/PHY/NR_UE_TRANSPORT/nr_initial_sync.c

openair1/PHY/NR_UE_TRANSPORT/nr_pbch.c

openair1/PHY/defs_nr_UE.h

targets/RT/USER/nr-ue.c