Internationalization (German) of the mobile app. (#246)

* Add i18n framework to mobile app and write simple translation generator

* Replace all texts in login_form with i18n keys

* Localization of sharing section

* Localization of asset viewer section

* Use JSON as base translation format

* Add check for missing/unused translation keys

* Add localizely

* Remove i18n directory in favour of localizely

* Backup Translation

* More translations

* Translate home page

* Translation of search page

* Translate new server version announcement

* Reformat code

* Fix typo in german translation

* Update englisch translations

* Change translation keys to match dart filenames

* Add /api to translated endpoint_urls

* Update localizely.yml

* Add languages to ios plist

* Remove unused keys

* Added script to check outdated key in other translations

* Add download key to localizely.yml

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

mobile/lib/modules/sharing/views/album_viewer_page.dart

@@ -1,4 +1,5 @@
 import 'package:auto_route/auto_route.dart';
+import 'package:easy_localization/easy_localization.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_hooks/flutter_hooks.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
@@ -204,13 +205,13 @@ class AlbumViewerPage extends HookConsumerWidget {
               AlbumActionOutlinedButton(
                 iconData: Icons.add_photo_alternate_outlined,
                 onPressed: () => _onAddPhotosPressed(albumInfo),
-                labelText: "Add photos",
+                labelText: "share_add_photos".tr(),
               ),
               if (userId == albumInfo.ownerId)
                 AlbumActionOutlinedButton(
                   iconData: Icons.person_add_alt_rounded,
                   onPressed: () => _onAddUsersPressed(albumInfo),
-                  labelText: "Add users",
+                  labelText: "album_viewer_page_share_add_users".tr(),
                 ),
             ],
           ),