add multiselect and movie tags (#62)

* add basic selection behavior to search results

* add search scrolling, selection actions

* include shows in multiselect

* multiselect movies, shows, collection items

* add movie and show tags

* code cleanup

* update show screenshot

ErsatzTV.Core.Tests/Fakes/FakeMediaCollectionRepository.cs

@@ -16,6 +16,8 @@ namespace ErsatzTV.Core.Tests.Fakes
         public FakeMediaCollectionRepository(Map<int, List<MediaItem>> data) => _data = data;
         public Task<Collection> Add(Collection collection) => throw new NotSupportedException();
         public Task<bool> AddMediaItem(int collectionId, int mediaItemId) => throw new NotSupportedException();
+        public Task<bool> AddMediaItems(int collectionId, List<int> mediaItemIds) => throw new NotSupportedException();
+
         public Task<Option<Collection>> Get(int id) => throw new NotSupportedException();
         public Task<Option<Collection>> GetCollectionWithItems(int id) => throw new NotSupportedException();
         public Task<Option<Collection>> GetCollectionWithItemsUntracked(int id) => throw new NotSupportedException();

ErsatzTV.Core.Tests/Fakes/FakeTelevisionRepository.cs

@@ -9,6 +9,8 @@ namespace ErsatzTV.Core.Tests.Fakes
 {
     public class FakeTelevisionRepository : ITelevisionRepository
     {
+        public Task<bool> AllShowsExist(List<int> showIds) => throw new NotSupportedException();
+
         public Task<bool> Update(Show show) => throw new NotSupportedException();
 
         public Task<bool> Update(Season season) => throw new NotSupportedException();