Add Movie Collections Support

[mmcdole]

Add support for browsing movie collections (e.g., Godfather trilogy, Harry Potter series) within the Movies library.

Question: How should collections be navigated? Should they appear as a category when browsing Movies, similar to "All Movies" or "Recently Added"? Or integrate differently into the navigation?

[exaSR]

I see some options here:

1. Add a new main category "Collections"
2. Add a "Collections" folder below Movies; as first entry.
3. Add each collection as subfolder within the movie list, just like TV show seasons work.
4. "Unpack" the collection and prefix the contained movies accordingly
5. Ignore the collection status and add collection entries to the main Movies list.

Depending on implementation effort, (5) might be a good first release?