add metrics, tracing, validation interceptors, add options: WithInterceptors, With{Client,Server}Interceptors

interceptors/interceptors.go

@@ -0,0 +1,20 @@
+package interceptors
+
+import (
+	"google.golang.org/grpc"
+)
+
+type ServerInterceptors interface {
+	UnaryServerInterceptor() grpc.UnaryServerInterceptor
+	StreamServerInterceptor() grpc.StreamServerInterceptor
+}
+
+type ClientInterceptors interface {
+	UnaryClientInterceptor() grpc.UnaryClientInterceptor
+	StreamClientInterceptor() grpc.StreamClientInterceptor
+}
+
+type Interceptors interface {
+	ServerInterceptors
+	ClientInterceptors
+}