fix ReadableNativeMap.getNullableValue to match signature (#30121)

Summary:
This PR changes ReadableNativeMap.getNullableValue to return null if key not found, instead of throwing exception. This matches method signature and nullable annotation.

## Changelog

[Android] [Changed] - fix ReadableNativeMap.getNullableValue to match signature

Pull Request resolved: #30121

Test Plan: RNTester app builds and runs as expected, and getNullableValue will return null instead of throwing exception.

Reviewed By: JoshuaGross

Differential Revision: D24164302

Pulled By: fkgozali

fbshipit-source-id: 572c1d4ae5fd493aa0018c2df1dfc7fc91cb4b6b

ReactAndroid/src/main/java/com/facebook/react/bridge/ReadableNativeMap.java

@@ -120,7 +120,7 @@ private <T> T getValue(String name, Class<T> type) {
     if (hasKey(name)) {
       return getLocalMap().get(name);
     }
-    throw new NoSuchKeyException(name);
+    return null;
   }
 
   private @Nullable <T> T getNullableValue(String name, Class<T> type) {