Made channel estimation techniques configurable

executables/nr-gnb.c

executables/nr-uesoftmodem.c

executables/nr-uesoftmodem.h

executables/softmodem-common.h

openair1/PHY/NR_ESTIMATION/nr_ul_channel_estimation.c

openair1/PHY/NR_REFSIG/dmrs_nr.c

openair1/PHY/NR_REFSIG/dmrs_nr.h

openair1/PHY/NR_TRANSPORT/nr_ulsch_demodulation.c

openair1/PHY/NR_UE_ESTIMATION/nr_dl_channel_estimation.c

openair1/PHY/NR_UE_TRANSPORT/nr_dlsch_demodulation.c

openair1/PHY/NR_UE_TRANSPORT/nr_transport_proto_ue.h

openair1/PHY/defs_gNB.h

openair1/PHY/defs_nr_UE.h

openair1/SCHED_NR_UE/phy_procedures_nr_ue.c

openair1/SIMULATION/NR_PHY/dlsim.c

openair1/SIMULATION/NR_PHY/ulsim.c