Better grouping of Collections

[beckfield 173]

While the recent addition of "Group By..." in Collections is a welcome addition, it falls a bit short of the requested feature, linked here:

https://emby.media/community/index.php?/topic/112513-feature-request-group-medialibrary-types-in-collections/

The request was to be able to group collections by Library type.  What was implemented is grouping by media type.  In the case of my Harry Potter collection, that means that audiobooks and soundtracks are still mixed together, since they are all CDs.  If grouping were done by Library type, these could be segregated as well.