T1002191 enable new wizard elements

I found a way to auto enable new wizard entries. Together with #748 this solves the last known problem of the new wizard.

They get only enabled once (the first time an IDE with the new wizards is started) and then never again.
It would be better to use the constant string defined somewhere in `ScalaPlugin` instead of this string. Might be worth adding the wizard-specific strings as constants as well.