118 - Implement shared album feature (#124)

* New features 
  - Share album. Users can now create albums to share with existing people on the network.
  - Owner can delete the album.
  - Owner can invite the additional users to the album.
  - Shared users and the owner can add additional assets to the album.
* In the asset viewer, the user can swipe up to see detailed information and swip down to dismiss.
* Several UI enhancements.

mobile/lib/modules/sharing/models/asset_selection_page_result.model.dart

@@ -0,0 +1,70 @@
+import 'dart:convert';
+
+import 'package:collection/collection.dart';
+
+import 'package:immich_mobile/shared/models/immich_asset.model.dart';
+
+class AssetSelectionPageResult {
+  final Set<ImmichAsset> selectedNewAsset;
+  final Set<ImmichAsset> selectedAdditionalAsset;
+  final bool isAlbumExist;
+
+  AssetSelectionPageResult({
+    required this.selectedNewAsset,
+    required this.selectedAdditionalAsset,
+    required this.isAlbumExist,
+  });
+
+  AssetSelectionPageResult copyWith({
+    Set<ImmichAsset>? selectedNewAsset,
+    Set<ImmichAsset>? selectedAdditionalAsset,
+    bool? isAlbumExist,
+  }) {
+    return AssetSelectionPageResult(
+      selectedNewAsset: selectedNewAsset ?? this.selectedNewAsset,
+      selectedAdditionalAsset: selectedAdditionalAsset ?? this.selectedAdditionalAsset,
+      isAlbumExist: isAlbumExist ?? this.isAlbumExist,
+    );
+  }
+
+  Map<String, dynamic> toMap() {
+    final result = <String, dynamic>{};
+
+    result.addAll({'selectedNewAsset': selectedNewAsset.map((x) => x.toMap()).toList()});
+    result.addAll({'selectedAdditionalAsset': selectedAdditionalAsset.map((x) => x.toMap()).toList()});
+    result.addAll({'isAlbumExist': isAlbumExist});
+
+    return result;
+  }
+
+  factory AssetSelectionPageResult.fromMap(Map<String, dynamic> map) {
+    return AssetSelectionPageResult(
+      selectedNewAsset: Set<ImmichAsset>.from(map['selectedNewAsset']?.map((x) => ImmichAsset.fromMap(x))),
+      selectedAdditionalAsset:
+          Set<ImmichAsset>.from(map['selectedAdditionalAsset']?.map((x) => ImmichAsset.fromMap(x))),
+      isAlbumExist: map['isAlbumExist'] ?? false,
+    );
+  }
+
+  String toJson() => json.encode(toMap());
+
+  factory AssetSelectionPageResult.fromJson(String source) => AssetSelectionPageResult.fromMap(json.decode(source));
+
+  @override
+  String toString() =>
+      'AssetSelectionPageResult(selectedNewAsset: $selectedNewAsset, selectedAdditionalAsset: $selectedAdditionalAsset, isAlbumExist: $isAlbumExist)';
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) return true;
+    final setEquals = const DeepCollectionEquality().equals;
+
+    return other is AssetSelectionPageResult &&
+        setEquals(other.selectedNewAsset, selectedNewAsset) &&
+        setEquals(other.selectedAdditionalAsset, selectedAdditionalAsset) &&
+        other.isAlbumExist == isAlbumExist;
+  }
+
+  @override
+  int get hashCode => selectedNewAsset.hashCode ^ selectedAdditionalAsset.hashCode ^ isAlbumExist.hashCode;
+}