Refactoring. Add Tests.

cmd/ris-mirror/main.go

cmd/ris-mirror/rismirror/mirror.go

cmd/ris-mirror/rismirror/router.go

cmd/ris-mirror/rtmirror/routecontainer.go

cmd/ris-mirror/rtmirror/rtmirror.go

cmd/ris-mirror/rtmirror/rtmirror_test.go

metrics/vrf/adapter/prom/vrf_prom_adapter.go

route/path.go

route/route.go

route/static.go

routingtable/vrf/metrics.go

routingtable/vrf/metrics/vrf_metrics.go