[auth] Remove superfluous getCurrentUser method which doesn’t exist in API

lib/modules/auth/index.js

@@ -319,14 +319,6 @@ export default class Auth extends ModuleBase {
     return getNativeModule(this).checkActionCode(code);
   }
 
-  /**
-   * Get the currently signed in user
-   * @return {Promise}
-   */
-  getCurrentUser(): Promise<User | null> {
-    return this._interceptUserValue(getNativeModule(this).getCurrentUser());
-  }
-
   /**
    * Returns a list of authentication providers that can be used to sign in a given user (identified by its main email address).
    * @return {Promise}