add json to metadata response side support (#29460)

Signed-off-by: cqi1217 <caiqi1217@pinterest.com>

Mirrored from https://github.com/envoyproxy/envoy @ 3f3790dd6d589571b51f2edd5c61bb0fbc1fcd76

envoy/extensions/filters/http/json_to_metadata/v3/json_to_metadata.proto

@@ -110,6 +110,10 @@ message JsonToMetadata {
     bool allow_empty_content_type = 3;
   }
 
-  // Rules to match json body of requests
-  MatchRules request_rules = 1 [(validate.rules).message = {required: true}];
+  // At least one of request_rules and response_rules must be provided.
+  // Rules to match json body of requests.
+  MatchRules request_rules = 1;
+
+  // Rules to match json body of responses.
+  MatchRules response_rules = 2;
 }