[Console] Added the possibility to set a different default command

* Added new method `setDefaultCommand` and changed the logic in the doRun
method in order to allow it to run by default a Command setted by the user
instead of the `ListCommand`
* Added tests
* Should fix #8058
* Updated CHANGELOG
Merge branch 'ticket_8058' of github.com:danielcsgomes/symfony into ticket_8058