refactor(mobile): more repositories (#12879)

* ExifInfoRepository
 * ActivityApiRepository
 * initial AssetApiRepository

mobile/lib/repositories/base_api.repository.dart

@@ -0,0 +1,11 @@
+import 'package:flutter/foundation.dart';
+import 'package:immich_mobile/constants/errors.dart';
+
+abstract class BaseApiRepository {
+  @protected
+  Future<T> checkNull<T>(Future<T?> future) async {
+    final response = await future;
+    if (response == null) throw NoResponseDtoError();
+    return response;
+  }
+}