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* Added script to check outdated key in other translations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/asset_selection_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';
@@ -65,9 +66,9 @@ class AssetSelectionPage extends HookConsumerWidget {
         ),
         title: selectedAssets.isEmpty
             ? const Text(
-                'Add photos',
+                'share_add_photos',
                 style: TextStyle(fontSize: 18),
-              )
+              ).tr()
             : Text(
                 _buildAssetCountText(),
                 style: const TextStyle(fontSize: 18),
@@ -86,9 +87,9 @@ class AssetSelectionPage extends HookConsumerWidget {
                 AutoRouter.of(context).pop(payload);
               },
               child: const Text(
-                "Add",
+                "share_add",
                 style: TextStyle(fontWeight: FontWeight.bold),
-              ),
+              ).tr(),
             ),
         ],
       ),