Issue 837: Stopping the server in host mode doesn't invoke Client.Disconnected on host client

Repository: miragenet/mirage

Issue body:
**Describe the bug**
Calling `Server.Stop()` in host mode does not lead to `Client.Disconnected` event being called for the local client, which is a regression.

**To Reproduce**
1. Call `Server.Stop()` in host mode.
2. Observe `Client.Disconnected` not being tiriggered.
