Add remote write proto v2

Signed-off-by: SungJin1212 <[email protected]>

Author: SungJin1212

Makefile

@@ -85,6 +85,7 @@ $(foreach exe, $(EXES), $(eval $(call dep_exe, $(exe))))
 
 # Manually declared dependencies And what goes into each exe
 pkg/cortexpb/cortex.pb.go: pkg/cortexpb/cortex.proto
+pkg/cortexpbv2/cortexv2.pb.go: pkg/cortexpbv2/cortexv2.proto
 pkg/ingester/client/ingester.pb.go: pkg/ingester/client/ingester.proto
 pkg/distributor/distributorpb/distributor.pb.go: pkg/distributor/distributorpb/distributor.proto
 pkg/ingester/wal.pb.go: pkg/ingester/wal.proto