Close the TermControl when closing a TerminalPaneContent (#19657)

This fixes an issue where calling close on a tab/pane won't
raise a StateChange notification on the connection.

src/cascadia/TerminalApp/TerminalPaneContent.cpp

@@ -66,8 +66,12 @@ namespace winrt::TerminalApp::implementation
     }
     void TerminalPaneContent::Close()
     {
+        // We deliberately remove the event handlers before closing the control.
+        // This is to prevent reentrancy issues, pointless callbacks, etc.
         _removeControlEvents();
 
+        _control.Close();
+
         // Clear out our media player callbacks, and stop any playing media. This
         // will prevent the callback from being triggered after we've closed, and
         // also make sure that our sound stops when we're closed.