cask/artifact/moved: fix permission handling when removing directories

[Bo98]

While target.parent.writable? is a sufficient check if we can remove a file or an empty directory, it is insufficient to test whether we can remove the entire directory tree as the directory itself and all non-empty recursive subdirectories will need write permissions. Utils.gain_permissions_remove already handles this for us so use it unconditionally.

Note that using Utils.gain_permissions_remove doesn't mean that sudo will always be used - it will still try to remove without sudo if possible.

[Bo98]

Not entirely sure why there's a test that expects uninstalling to fail? Seems really weird to be perfectly ok raising permission if the parent directory isn't writable but not if a child directory is.

[MikeMcQuaid]

Makes sense, thanks @Bo98!

[MikeMcQuaid]

Seems really weird to be perfectly ok raising permission if the parent directory isn't writable but not if a child directory is.

Agreed.