Added the ability to reconnect a terminal using Ctrl+R after a connection terminates or breaks

The fact that connections can now be re-connected has also motivated me to change the behavior when navigating away from disconnected connections (using the top app bar).
Until now such connections were deemed not useful anymore and were automatically removed from the connection manager. Thus they didn't appear in the top app bar on the favorites page and the connection page anymore.
This was changed so that these connections are not automatically removed anymore, they are marked with a red border and have to be closed with the  button in the top app bar.