improve scanning, add refresh button to media cards (#23)

* support .etvignore files to exclude folders (and child folders) from scanner

* include top-level folder in scanner

* don't always rescan "other" media sources

* add metadata/poster refresh button to media cards

ErsatzTV.Application/MediaItems/AggregateMediaItemViewModel.cs

@@ -1,6 +1,7 @@
 namespace ErsatzTV.Application.MediaItems
 {
     public record AggregateMediaItemViewModel(
+        int MediaItemId,
         string Title,
         string Subtitle,
         string SortTitle,

ErsatzTV.Application/MediaItems/Commands/RefreshMediaItemPosterHandler.cs

@@ -0,0 +1,45 @@
+using System.Threading;
+using System.Threading.Tasks;
+using ErsatzTV.Core;
+using ErsatzTV.Core.Domain;
+using ErsatzTV.Core.Interfaces.Metadata;
+using ErsatzTV.Core.Interfaces.Repositories;
+using LanguageExt;
+
+namespace ErsatzTV.Application.MediaItems.Commands
+{
+    public class
+        RefreshMediaItemPosterHandler : MediatR.IRequestHandler<RefreshMediaItemPoster,
+            Either<BaseError, Unit>>
+    {
+        private readonly ILocalPosterProvider _localPosterProvider;
+        private readonly IMediaItemRepository _mediaItemRepository;
+
+        public RefreshMediaItemPosterHandler(
+            IMediaItemRepository mediaItemRepository,
+            ILocalPosterProvider localPosterProvider)
+        {
+            _mediaItemRepository = mediaItemRepository;
+            _localPosterProvider = localPosterProvider;
+        }
+
+        public Task<Either<BaseError, Unit>> Handle(
+            RefreshMediaItemPoster request,
+            CancellationToken cancellationToken) =>
+            Validate(request)
+                .MapT(RefreshPoster)
+                .Bind(v => v.ToEitherAsync());
+
+        private Task<Validation<BaseError, MediaItem>> Validate(RefreshMediaItemPoster request) =>
+            MediaItemMustExist(request);
+
+        private Task<Validation<BaseError, MediaItem>> MediaItemMustExist(RefreshMediaItemPoster request) =>
+            _mediaItemRepository.Get(request.MediaItemId)
+                .Map(
+                    maybeItem => maybeItem.ToValidation<BaseError>(
+                        $"[MediaItem] {request.MediaItemId} does not exist."));
+
+        private Task<Unit> RefreshPoster(MediaItem mediaItem) =>
+            _localPosterProvider.RefreshPoster(mediaItem).ToUnit();
+    }
+}

ErsatzTV.Application/MediaItems/Queries/GetAggregateMediaItemsHandler.cs

@@ -30,6 +30,7 @@ namespace ErsatzTV.Application.MediaItems.Queries
             var results = allItems
                 .Map(
                     s => new AggregateMediaItemViewModel(
+                        s.MediaItemId,
                         s.Title,
                         s.Subtitle,
                         s.SortTitle,