fix(iOS): unify prefetchImageWithMetadata's signature in JS and ObjC land (facebook#47532)

Summary:
in `prefetchImageWithMetadata`'s implementation in ObjC, the method's `queryRootName` is treated as being nullable. The image spec for it in JS (and the Codegened ObjC header that gets built on top of it) treat the field as not nullable. This change makes the field nullable in the spec to match up what we have in the implementation.

I also noticed that the method is not defined in the [Image props](https://reactnative.dev/docs/image) on the RN website, so perhaps we should add this there as well.

## Changelog:

[IOS] [CHANGED] - make `prefetchImageWithMetadata`'s `queryRootName` nullable in the spec

Pull Request resolved: facebook#47532

Test Plan:
yarn test:
<img width="1576" alt="Screenshot 2024-11-09 at 00 36 30" src="https://github.com/user-attachments/assets/4162ff79-1388-4f6f-9576-256fd9011fcf">
It has no iOS specific tests, so nothing to run on that side

Differential Revision: D66093745

Pulled By: cipolleschi

Author: TheRogue76

packages/react-native/Libraries/Image/Image.ios.js

@@ -72,7 +72,7 @@ function getSizeWithHeaders(
 
 function prefetchWithMetadata(
   url: string,
-  queryRootName: string,
+  queryRootName: ?string,
   rootTag?: ?RootTag,
 ): Promise<boolean> {
   if (NativeImageLoaderIOS.prefetchImageWithMetadata) {

packages/react-native/src/private/specs/modules/NativeImageLoaderIOS.js

@@ -28,7 +28,7 @@ export interface Spec extends TurboModule {
   +prefetchImage: (uri: string) => Promise<boolean>;
   +prefetchImageWithMetadata?: (
     uri: string,
-    queryRootName: string,
+    queryRootName: ?string,
     rootTag: RootTag,
   ) => Promise<boolean>;
   +queryCache: (uris: Array<string>) => Promise<Object>;