Fix favorites view redrawing

Shared/Favorites/FavoriteResourceObserver.swift

@@ -0,0 +1,22 @@
+import Foundation
+import Siesta
+
+final class FavoriteResourceObserver: ObservableObject, ResourceObserver {
+    @Published var videos = [Video]()
+
+    func resourceChanged(_ resource: Resource, event _: ResourceEvent) {
+        if let videos: [Video] = resource.typedContent() {
+            self.videos = videos
+        } else if let channel: Channel = resource.typedContent() {
+            videos = channel.videos
+        } else if let playlist: ChannelPlaylist = resource.typedContent() {
+            videos = playlist.videos
+        } else if let playlist: Playlist = resource.typedContent() {
+            videos = playlist.videos
+        }
+    }
+
+    var contentItems: [ContentItem] {
+        videos.map { ContentItem(video: $0) }
+    }
+}