Application appears to hang when running code after Closing current session

[Becky-Williamson]

Steps to reproduce:

1. Connect to 9.4 via ssh connection.
2. Run code that creates a table in the WORK library (data test; set sashelp.class; run;)
3. Run code that prints the contents of the table in the WORK library (proc print data=test; run;)
4. Click the icon to Close current session.
5. Run the code in step 3 again.

Expected results:
I would expect to get an error, either than I wasn't connected or, if it reconnects on run, that the table doesn't exist.

Actual results:
No entry is made in the log and the notification in the bottom right corner just continues to say SAS code running. I let it go for about a half hour and it never finished. I had to restart VS Code to get out of it.

Found while testing pull request #160

[Becky-Williamson]

NOTE: When connected to Viya, the application automatically reconnects to the session and the code runs with no errors.

[smorrisj]

Working with @Becky-Williamson to reproduce. I'm in the process of building an instrumented version of the ssh connection code to isolate where the hang is occurring. I'm unable to rep locally or when building a vsce package and side loading on a windows virtual machine.

[smorrisj]

I was able to identify the issue. Calling stream.end("exit") was creating a case where if there is non-trivial latency on the ssh connection to the server, that it's possible that the connection has not fully closed on both sides before the setup function was invoked again when pressing the run button.

We should update the close implementation to use stream.close() instead. The onClose listener is responsible for closing the connection itself.

Fixed on #160

[smorrisj]

Fix verified on #160. Closing.