Improve WebSocket connection handling

[maciaszczykm]

What would you like to be added? / User Story: At the moment WebSocket added in #2008 is handled through 2 subjects. One of them is a representation of connection with the API, the second one acts like a proxy that is filtered from errors. We should check if we can improve it and remove the proxy subject to simplify things.

Example (not working in 100%):

  get adminSettings(): Observable<AdminSettings> {
    const webSocket$ = webSocket<AdminSettings>(`${this.wsRoot}/admin/settings`).pipe(
      startWith(DEFAULT_ADMIN_SETTINGS),
      catchError(() => onErrorResumeNext(EMPTY)),
      map(settings => this._defaultAdminSettings(settings)),
      shareReplay({refCount: true, bufferSize: 1})
    );

    return iif(() => this._auth.authenticated(), webSocket$, of(DEFAULT_ADMIN_SETTINGS));
  }

[maciaszczykm]

The method above is very close to the one that we are using right now but the retry mechanism doesn't work that well. If error occurs when user is for example in the admin settings then an error is produced anyways. I will close it as the current way seems to work as it should and is more error-proof.