pollDeviceCommands

Poll the server for any pending device commands.

💾 This method alters the persisted account state.

Applications that have registered one or more `DeviceCapability`s with the server can use this method to check whether other devices on the account have sent them any commands. It will return a list of `IncomingDeviceCommand` structs for the application to process.

Notes

- Device commands are typically delivered via push message and the [`CommandReceived`](
  AccountEvent::CommandReceived) event. Polling should only be used as a backup delivery
  mechanism, f the application has reason to believe that push messages may have been missed.
- Device commands functionality is only available to applications that have been
  granted the `https:///identity.mozilla.com/apps/oldsync` scope.