map-controller: beacon metrics query & response

src/core/cntlr.c

src/core/cntlr.h

src/core/cntlr_cmdu_generator.c

src/core/cntlr_cmdu_generator.h

src/core/cntlr_map.c

src/core/cntlr_tlv_generator.c

src/core/cntlr_tlv_generator.h

src/core/cntlr_ubus.c