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* Added script to check outdated key in other translations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>

localizely.yml

@@ -0,0 +1,15 @@
+config_version: 1.0
+project_id: ead34689-ec52-41d9-b675-09bc85a6cbd7
+file_type: flutter_arb
+upload:
+  files:
+    - file: mobile/assets/i18n/en-US.json
+      locale_code: en
+    - file: mobile/assets/i18n/de-DE.json
+      locale_code: de
+download:
+  files:
+    - file: mobile/assets/i18n/en-US.json
+      locale_code: en
+    - file: mobile/assets/i18n/de-DE.json
+      locale_code: de