Allow compilation of index.agda under 2.3.2.2

`homotopy.SuspensionJoin` just required some rearranging, but `lib.types.PathSeq` is not at fault for its failure to compile.  I added `homotopy.SuspensionJoin` to `index`, and commented out `homotopy.Hopf`, which depends on `lib.types.PathSeq`.