fix: improve stopping logic

[jacobheun]

This includes code from #322 and builds off of it to fix some other stopping issues.

1. Connections weren't allowing disconnect when upgrading. So if a close was attempted while muxing was being negotiated the connection wouldn't close. I updated an existing test to better catch this.
2. When stopping, if a listener errors during close it would cause stopping to fail. This change logs the error out and continues on with stopping the switch to ensure all connections are terminated.

Also, if starting errored it would only log the error out and not stop the switch, this corrects that.