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* Added script to check outdated key in other translations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/asset_viewer/ui/exif_bottom_sheet.dart

@@ -1,3 +1,4 @@
+import 'package:easy_localization/easy_localization.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_map/flutter_map.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
@@ -72,7 +73,7 @@ class ExifBottomSheet extends ConsumerWidget {
         children: [
           if (assetDetail.exifInfo?.dateTimeOriginal != null)
             Text(
-              DateFormat('E, LLL d, y • h:mm a').format(
+              DateFormat('date_format'.tr()).format(
                 DateTime.parse(assetDetail.exifInfo!.dateTimeOriginal!),
               ),
               style: TextStyle(
@@ -84,12 +85,12 @@ class ExifBottomSheet extends ConsumerWidget {
           Padding(
             padding: const EdgeInsets.only(top: 16.0),
             child: Text(
-              "Add Description...",
+              "exif_bottom_sheet_description",
               style: TextStyle(
                 color: Colors.grey[500],
                 fontSize: 11,
               ),
-            ),
+            ).tr(),
           ),
 
           // Location
@@ -104,9 +105,9 @@ class ExifBottomSheet extends ConsumerWidget {
                     color: Colors.grey[600],
                   ),
                   Text(
-                    "LOCATION",
+                    "exif_bottom_sheet_location",
                     style: TextStyle(fontSize: 11, color: Colors.grey[400]),
-                  ),
+                  ).tr(),
                   if (assetDetail.exifInfo?.latitude != null &&
                       assetDetail.exifInfo?.longitude != null)
                     _buildMap(),
@@ -134,9 +135,9 @@ class ExifBottomSheet extends ConsumerWidget {
                   Padding(
                     padding: const EdgeInsets.only(bottom: 8.0),
                     child: Text(
-                      "DETAILS",
+                      "exif_bottom_sheet_details",
                       style: TextStyle(fontSize: 11, color: Colors.grey[400]),
-                    ),
+                    ).tr(),
                   ),
                   ListTile(
                     contentPadding: const EdgeInsets.all(0),