improve the license score categories unclearinformation and clearlyspecified

There were some inconsistencies in the license score, which are resolved in this MR. Note that other-open has a double function so far. It contains both unspecified open licenses and multiple open licenses. These cases should be treated differently in the metadata score, the first one corresponds to UnclearInformation, the latter one to ClearlySpecifiedAndFree. To account for this, the latter are assigned to a new subcategory Mixed within the category Open