License enforcement

Primarily. this adds a check to inquisitor to ensure that mirroring is restricted for mods that don't have a re-distributable license.

To be honest I think we could probably just use the licence group to determine if a file can be mirrored and make RESTRICT=mirror unnecessary (fetch would still be necessary). That being said, having the extra validation is useful. Perhaps the best way is to mirror files with licenses that are in the redistributable group and don't have restricted fetch or restricted mirror set.

Edit: It's worth noting that mods that contain multiple sources, some of which are redistributable and some of which aren't, should not be considered redistributable, as we don't currently have a mechanism for tying licenses to a single source. Such mods should have restricted mirroring enabled, but for other mods we can safely make it implicit using their license.

Edit 2: New version. Use use-reduce and check licenses. We now check license string and if all groups are redistributable (noting support of || groups), we mirror the file.