Resolve static methods of enum in front-end

Up to this point, front-end did not suspect that there could be classes which
have both a class object and a package for static members. Since this became
possible for enums loaded from Java binaries (enum entries and valueOf()/
values() are placed into the class object, and every other static member into
the package), we adjust the corresponding scope to also include members from
the corresponding package

 #KT-2990 Fixed