Unrequire command

Currently, to remove a package it is necessary to manually execute the following operations:
1. remove the package from _composer.json_
2. remove the package from _composer.lock_
3. remove the orphaned dependencies from _composer.lock_
4. run `composer install`
With this command, instead, it is enough to tun `composer unrequire mypackage` and the package will be removed with all the orphaned dependencies.