fix: singletonMap for module events (#42354)

Summary:
Sometimes the events map can be a of type `SingletonMap` which will cause this code to throw exception when adding keys to it, so we change it to normal `HashMap`. Creating `SingletonMap` can especially happen in Kotlin when there is only one event added to a map, see:
https://github.com/plaid/react-native-plaid-link-sdk/blob/5ffab5eef576163528f0da504181162da3bef08b/android/src/main/java/com/plaid/PLKEmbeddedViewManager.kt#L21
## Changelog:

[ANDROID] [FIXED] - Cover SingletonMap when parsing events exported by module

Pull Request resolved: #42354

Test Plan: Create `getExportedCustomBubblingEventTypeConstants` as `SingletonMap` in some example module and see that the code does not throw.

Reviewed By: cipolleschi

Differential Revision: D58417266

Pulled By: cortinico

fbshipit-source-id: 6c46398ddf4d044386a36d0c1663bd071d642fb6

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerModuleConstantsHelper.java

@@ -193,6 +193,11 @@ private static void validateDirectEventNames(
         }
       }
     }
+    // When providing one event in Kotlin, it will create a SingletonMap by default
+    // which will throw on trying to add new element to it
+    if (!(events instanceof HashMap)) {
+      events = new HashMap(events);
+    }
     for (String oldKey : keysToNormalize) {
       Object value = events.get(oldKey);
       String baseKey = "";