[GUI] Ctrl + S should also save current project as recently opened project

Problem to solve

Recently opened project are accessible in the GUI via Project -> Open Recent. At the moment, this list is only saved when closing Vadere.

It would be good if this list is also stored when using the shortcut "Ctrl + S" (to store a scenario). This is useful if Vadere crashes during a simulation run. Then, after re-opening Vadere, the user would be prompted with the project which was opened before Vadere has crashed.