feat(mobile): Library page rework (album sorting, favorites) (#1501)

* Add album sorting

* Change AppBar to match photos page behaviour

* Add buttons

* First crude implementation of the favorites page

* Clean up

* Add favorite button

* i18n

* Add star indicator to thumbnail

* Add favorite logic to separate provider and fix favorite behavior in album

* Review feedback (Add isFavorite variable)

* dev: style buttons

* dev: styled drop down button

---------

Co-authored-by: Alex Tran <alex.tran1502@gmail.com>

mobile/lib/modules/favorite/providers/favorite_provider.dart

@@ -0,0 +1,52 @@
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:immich_mobile/shared/models/asset.dart';
+import 'package:immich_mobile/shared/providers/asset.provider.dart';
+
+class FavoriteSelectionNotifier extends StateNotifier<Set<String>> {
+  FavoriteSelectionNotifier(this.ref) : super({}) {
+    state = ref.watch(assetProvider).allAssets
+        .where((asset) => asset.isFavorite)
+        .map((asset) => asset.id)
+        .toSet();
+  }
+
+  final Ref ref;
+
+  void _setFavoriteForAssetId(String id, bool favorite) {
+    if (!favorite) {
+      state = state.difference({id});
+    } else {
+      state = state.union({id});
+    }
+  }
+
+  bool _isFavorite(String id) {
+    return state.contains(id);
+  }
+
+  Future<void> toggleFavorite(Asset asset) async {
+    if (!asset.isRemote) return; // TODO support local favorite assets
+
+    _setFavoriteForAssetId(asset.id, !_isFavorite(asset.id));
+
+    await ref.watch(assetProvider.notifier).toggleFavorite(
+      asset,
+      state.contains(asset.id),
+    );
+  }
+}
+
+final favoriteProvider =
+    StateNotifierProvider<FavoriteSelectionNotifier, Set<String>>((ref) {
+  return FavoriteSelectionNotifier(ref);
+});
+
+final favoriteAssetProvider = StateProvider((ref) {
+  final favorites = ref.watch(favoriteProvider);
+
+  return ref
+      .watch(assetProvider)
+      .allAssets
+      .where((element) => favorites.contains(element.id))
+      .toList();
+});