Neighbor configuration can be given by gNB.conf

get_MeasConfig function is extended as it will prepare A2 / A3 Report
Configs. Single Meas Obj is used for all.

rrc_gNB_process_MeasurementReport function is extended to process A2 /
A3 measurement events.  helper functions are written to fetch neighbour
cell informations from sequence containers.
(get_neighbour_cell_information, get_neighbour_config)