fix(app-check, types): add newReactNativeFirebaseAppCheckProvider function type

it was only missing due to oversight originally, apologies

Author: mikehardy

packages/app-check/__tests__/appcheck.test.ts

@@ -20,4 +20,10 @@ describe('appCheck()', function () {
       );
     });
   });
+
+  describe('react-native-firebase provider', function () {
+    it('correctly creates a provider instance', function () {
+      expect(firebase.appCheck().newReactNativeFirebaseAppCheckProvider()).toBeDefined();
+    });
+  });
 });

packages/app-check/lib/index.d.ts

@@ -193,6 +193,11 @@ export namespace FirebaseAppCheckTypes {
    *
    */
   export class Module extends FirebaseModule {
+    /**
+     * create a ReactNativeFirebaseAppCheckProvider option for use in react-native-firebase
+     */
+    newReactNativeFirebaseAppCheckProvider(): ReactNativeFirebaseAppCheckProvider;
+
     /**
      * initialize the AppCheck module. Note that in react-native-firebase AppCheckOptions must always
      * be an object with a `provider` member containing `ReactNativeFirebaseAppCheckProvider` that has returned successfully