Refactor: move error to corresponding pkg

Signed-off-by: Neeraj Gupta <254676+ua741@users.noreply.github.com>

lib/core/errors.dart

@@ -51,3 +51,5 @@ class InvalidStateError extends AssertionError {
 }
 
 class KeyDerivationError extends Error {}
+
+class SharingNotPermittedForFreeAccountsError extends Error {}

lib/services/collections_service.dart

@@ -1198,5 +1198,3 @@ class CollectionsService {
     }
   }
 }
-
-class SharingNotPermittedForFreeAccountsError extends Error {}

lib/ui/actions/collection/collection_sharing_actions.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:logging/logging.dart';
 import 'package:photos/core/configuration.dart';
+import "package:photos/core/errors.dart";
 import 'package:photos/db/files_db.dart';
 import 'package:photos/ente_theme_data.dart';
 import "package:photos/generated/l10n.dart";