* Cascadia/TerminalConnection: Close the output thread on exit.
It seems that TerminateThread() is available in the code...
* VtPipeTerm: Don't crash when closing the app.
- Gracefully handle ReadFile returning false (usually because of ERROR_BROKEN_PIPE on exit).
- Minor whitespace formatting.
* Cascadia/TerminalConnection: Finish to implement the ConhostConnection::Close() 'TODO' block.