Exclude raw props from view shadow nodes

Summary:
With the `MapBuffer`-based props calculated from C++ props, there's no need to keep `rawProps` around for Android views.

This change makes sure that the `rawProps` field is only initialized under the feature flag that is responsible for enabling `MapBuffer` for prop diffing, potentially decreasing memory footprint and speeding up node initialization as JS props don't have to be converted to `folly::dynamic` anymore.

For layout animations, props rely on C++ values, so there's no need to update `rawProps` values either.

Changelog: [Internal][Android] - Do not init `rawProps` when mapbuffer serialization is used for ViewProps.

Reviewed By: mdvacca

Differential Revision: D33793044

fbshipit-source-id: 35873b10d3ca8b152b25344ef2c27aff9641846f

ReactAndroid/src/main/java/com/facebook/react/fabric/jni/FabricMountingManager.cpp

@@ -223,6 +223,9 @@ local_ref<jobject> FabricMountingManager::getProps(
     ShadowView const &newShadowView) {
   if (useMapBufferForViewProps_ &&
       newShadowView.traits.check(ShadowNodeTraits::Trait::View)) {
+    react_native_assert(
+        newShadowView.props->rawProps.empty() &&
+        "Raw props must be empty when views are using mapbuffer");
     auto oldProps = oldShadowView.props != nullptr
         ? static_cast<ViewProps const &>(*oldShadowView.props)
         : ViewProps{};