[auth] constructing an new instance of an auth provider class will now throw an unsupported error

lib/modules/auth/providers/GithubAuthProvider.js

@@ -1,6 +1,10 @@
 const providerId = 'github';
 
 export default class GithubAuthProvider {
+  constructor() {
+    throw new Error('`new GithubAuthProvider()` is not supported on react-native-firebase.');
+  }
+
   static get PROVIDER_ID() {
     return providerId;
   }
@@ -12,8 +16,4 @@ export default class GithubAuthProvider {
       providerId,
     };
   }
-
-  get providerId() {
-    return providerId;
-  }
-};
+}