New tab on show page to display watched state

[mregni]

Add a new tab to the show page that will display a list of all shows and there watched percentage. This tab will need some filters as well to a user can filter on "Emby user". This data is also useful on the user detail page itself.

• [ ] Create a new tab and display list of shows
• [ ] Sync watched states from Emby on media sync (or small sync)
• [ ] Accumulate all watched states from all users and display progress bars
• [ ] Add a filter so a user can see watched state for a certain Emby user

Issue created because of #827