Feature request: add a unlink-all command

[tdwesten]

Hi There,

I would love to have a composer unlink --all or composer unlink-all command to unlink multiple packages.

[SanderSander]

@tdwesten At the moment it's possible to unlink all packages with composer unlink "../*" but this will only unlink all packages from the targeted directory.

But yeah I agree it would be nice to have a command that simply unlinks all packages wherever they came from.