Fabric: Remove designated initializers in Events and Mounting (#23441)

Summary:
This pull request removes the designated initializers in `react/mounting/**` and `react/events/**` to improve portability.

A destructor was also defined for `ShadowView` to fix this error:

```
ShadowViewMutation.cpp:14: error: undefined reference to 'facebook::react::ShadowView::~ShadowView()'
ShadowViewMutation.cpp:24: error: undefined reference to 'facebook::react::ShadowView::~ShadowView()'
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
```

[General] [Changed] - Fabric: Remove designated initializers in Events and Mounting
Pull Request resolved: https://github.com/facebook/react-native/pull/23441

Differential Revision: D14298890

Pulled By: shergin

fbshipit-source-id: f5d8fc6e1f5968b94e8bb3ca0c3f0e81cf892f83

ReactCommon/fabric/core/events/EventBeatBasedExecutor.cpp

@@ -25,15 +25,19 @@ EventBeatBasedExecutor::EventBeatBasedExecutor(
 
 void EventBeatBasedExecutor::operator()(Routine routine, Mode mode) const {
   if (mode == Mode::Asynchronous) {
-    execute({.routine = std::move(routine)});
+    execute({
+        /* .routine = */ std::move(routine),
+    });
     return;
   }
 
   std::mutex mutex;
   mutex.lock();
 
-  execute({.routine = std::move(routine),
-           .callback = [&mutex]() { mutex.unlock(); }});
+  execute({
+      /* .routine = */ std::move(routine),
+      /* .callback = */ [&mutex]() { mutex.unlock(); },
+  });
 
   mutex.lock();
 }

ReactCommon/fabric/mounting/ShadowView.h

@@ -23,6 +23,8 @@ struct ShadowView final {
   ShadowView() = default;
   ShadowView(const ShadowView &shadowView) = default;
 
+  ~ShadowView(){};
+
   /*
    * Constructs a `ShadowView` from given `ShadowNode`.
    */

ReactCommon/fabric/mounting/ShadowViewMutation.cpp

@@ -11,32 +11,49 @@ namespace facebook {
 namespace react {
 
 ShadowViewMutation ShadowViewMutation::CreateMutation(ShadowView shadowView) {
-  return ShadowViewMutation{
-      .type = Create, .newChildShadowView = shadowView, .index = -1};
+  return {
+      /* .type = */ Create,
+      /* .parentShadowView = */ {},
+      /* .newChildShadowView = */ shadowView,
+      /* .oldChildShadowView = */ {},
+      /* .index = */ -1,
+  };
 }
 
 ShadowViewMutation ShadowViewMutation::DeleteMutation(ShadowView shadowView) {
-  return {.type = Delete, .oldChildShadowView = shadowView, .index = -1};
+  return {
+      /* .type = */ Delete,
+      /* .parentShadowView = */ {},
+      /* .oldChildShadowView = */ shadowView,
+      /* .newChildShadowView = */ {},
+      /* .index = */ -1,
+  };
 }
 
 ShadowViewMutation ShadowViewMutation::InsertMutation(
     ShadowView parentShadowView,
     ShadowView childShadowView,
     int index) {
-  return {.type = Insert,
-          .parentShadowView = parentShadowView,
-          .newChildShadowView = childShadowView,
-          .index = index};
+  return {
+      /* .type = */ Insert,
+      /* .parentShadowView = */ parentShadowView,
+      /* .oldChildShadowView = */ {},
+      /* .newChildShadowView = */ childShadowView,
+      /* .index = */ index,
+  };
 }
 
 ShadowViewMutation ShadowViewMutation::RemoveMutation(
     ShadowView parentShadowView,
     ShadowView childShadowView,
     int index) {
-  return {.type = Remove,
-          .parentShadowView = parentShadowView,
-          .oldChildShadowView = childShadowView,
-          .index = index};
+  return {
+      /* .type = */ Remove,
+      /* .parentShadowView = */ parentShadowView,
+      /* .oldChildShadowView = */ childShadowView,
+      /* .newChildShadowView = */ {},
+      /* .index = */ index,
+  };
 }
 
 ShadowViewMutation ShadowViewMutation::UpdateMutation(
@@ -44,11 +61,13 @@ ShadowViewMutation ShadowViewMutation::UpdateMutation(
     ShadowView oldChildShadowView,
     ShadowView newChildShadowView,
     int index) {
-  return {.type = Update,
-          .parentShadowView = parentShadowView,
-          .oldChildShadowView = oldChildShadowView,
-          .newChildShadowView = newChildShadowView,
-          .index = index};
+  return {
+      /* .type = */ Update,
+      /* .parentShadowView = */ parentShadowView,
+      /* .oldChildShadowView = */ oldChildShadowView,
+      /* .newChildShadowView = */ newChildShadowView,
+      /* .index = */ index,
+  };
 }
 
 } // namespace react