Fabric: Universal fromDynamic for std::vector<...>

Summary:
Now, if `fromDynamic` is defined for some type, `fromDynamic` for `std::vector` of this type is also will be defined.
We need this for parsing `ImageSources` (a vector of `ImageSource`) type.

Reviewed By: fkgozali

Differential Revision: D8473508

fbshipit-source-id: d8dc8e3a3273f35b76c7132c553130762f768394

ReactCommon/fabric/core/propsConversions.h

@@ -24,6 +24,16 @@ inline void fromDynamic(const folly::dynamic &value, int &result) {
 }
 inline void fromDynamic(const folly::dynamic &value, std::string &result) { result = value.getString(); }
 
+template <typename T>
+inline void fromDynamic(const folly::dynamic &value, std::vector<T> &result) {
+  result.clear();
+  T itemResult;
+  for (auto &itemValue : value) {
+    fromDynamic(itemValue, itemResult);
+    result.push_back(itemResult);
+  }
+}
+
 template <typename T>
 inline T convertRawProp(
   const RawProps &rawProps,