chore: Move one instance of RCTUIView --> RCTPlatformView (#2639)

## Summary:

In general, we prefer to use `RCTPlatformView` (`#define NSView`) over
`RCTUIView` (subclass of NSView for iOS interop) as it tends to have
less "Expected NSView, but got subclass of NSView" style errors. This
changes fixes one of those errors

Author: Saadnajmi

packages/react-native/React/Fabric/Mounting/ComponentViews/LegacyViewManagerInterop/RCTLegacyViewManagerInteropComponentView.mm

@@ -244,7 +244,7 @@ - (void)finalizeUpdates:(RNComponentViewUpdateMask)updateMask
     NSNumber *index = mountInstruction[kRCTLegacyInteropChildIndexKey];
     RCTUIView *childView = mountInstruction[kRCTLegacyInteropChildComponentKey]; // [macOS]
     if ([childView isKindOfClass:[RCTLegacyViewManagerInteropComponentView class]]) {
-      RCTUIView *target = ((RCTLegacyViewManagerInteropComponentView *)childView).contentView; // [macOS]
+      RCTPlatformView *target = ((RCTLegacyViewManagerInteropComponentView *)childView).contentView; // [macOS]
       [_adapter.paperView insertReactSubview:target atIndex:index.integerValue];
     } else {
       [_adapter.paperView insertReactSubview:childView atIndex:index.integerValue];