OZG-7908 add double as possible payload element

aggregation-manager-interface/src/main/protobuf/aggregationdata.model.proto

@@ -57,9 +57,10 @@ message GrpcElement {
   oneof value {
     bool boolValue = 1;
     int64 longValue = 2;
-    string stringValue = 3;
-    GrpcElementList listValue = 4;
-    GrpcObject objectValue = 5;
+    double doubleValue = 3;
+    string stringValue = 4;
+    GrpcElementList listValue = 5;
+    GrpcObject objectValue = 6;
   }
 }