Realm.Credentials.serverApiKey and Realm.Credentials.userApiKey perform identical functions, so were marked as deprecated in https://github.com/realm/realm-js/commit/f54955a5ef7dff2d6bfb45483ecf351a68180cac#diff-52e30e256b42ae9eb24479069c555370865a9f9be570eabe2b097a1d01d867afR147 and superseded by a single Realm.Credentials.apiKey method.

This method was added to the web SDK: https://github.com/realm/realm-js/blob/master/packages/realm-web/src/Credentials.ts#L91 but was missed from the mobile SDK. This means that users see a deprecation warning for the old methods, but if they change their code to use apiKey, it will not work.

We need to add the apiKey method in https://github.com/realm/realm-js/blob/master/src/js_app_credentials.hpp#L51 and in the TS definitions. It should have the same implementation as server/userApiKey.