Firebase Firestore Database beta update

Updated the dependencies of the library to Firebase 11.6.0 and added checks of emitter.isDisposed in all the onError calls. This was caused a UncaughtException in cases where multiple onError were called at once and they are already disposed.

For example a disposables zip or merge where one of them fail. The first one call the whole onError for the disposable but each one of the single Observables will be disposed, and after that their onError will be called. Caused an UncaughtException