Allow creating Desktop (or Menu) shortcuts to launch a Godot version.

[bkmeneguello]

Describe the solution you'd like
Just a better workflow to #84. Maybe it could invoke the godot-manager executable with some arguments to select the desired version. This way the godot-manager can do some consistency checks before launching the godot executable.

[eumario]

I will see about implementing the option in the next point release, as an alternative to #84, both options would be available.