Add App Service Deployment to @realm/react tests

[takameyer]

At the moment, @realm/react is only testing against local realm. Anything App Service related is left untested or mocked out. The tests should have the capabilities of deploying a local or remote App Service to run tests against. It may also be worthwhile to mimick the integration tests so that @realm/react can be tested against various platforms, such as on device (simulator) React Native, electron and later with @realm/web.