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* Added script to check outdated key in other translations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/backup/ui/backup_info_card.dart

@@ -1,3 +1,4 @@
+import 'package:easy_localization/easy_localization.dart';
 import 'package:flutter/material.dart';
 
 class BackupInfoCard extends StatelessWidget {
@@ -44,7 +45,7 @@ class BackupInfoCard extends StatelessWidget {
               info,
               style: const TextStyle(fontSize: 24, fontWeight: FontWeight.bold),
             ),
-            const Text("assets"),
+            const Text("backup_info_card_assets").tr(),
           ],
         ),
       ),