dx clean, now cleans too much.

[ThomasCartier]

Hi,

dx 0.6.0 alpha1 from git.

executing a dx clean also deletes the artifacts folder. On my system, it happens to be a shared artifacts folder (out of tree), so it deletes everything there, even the artifacts of my other projects.

Maybe a test to know if we are located in the source folder could enable to select if we want to delete the parent folder as well or not.

Thanks!