config: add namespace support (#1780)

* config/cmd: use service namespace for config

* config/service: add namespace option to list

config/source/service/proto/service.proto

@@ -41,7 +41,9 @@ message DeleteRequest {
 
 message DeleteResponse {}
 
-message ListRequest {}
+message ListRequest {
+    string namespace = 1;
+}
 
 message ListResponse {
     repeated Change values = 1;