Mobile performance improvements (#417)

* First performance tweaks (caching and rendering improvemetns)

* Revert asset response caching

* 3-step image loading in asset viewer

* Prevent panning and zooming until full-scale version is loaded

* Loading indicator

* Adapt to gallery PR

* Cleanup

* Dart format

* Fix exif sheet

* Disable three stage loading until settings are available

mobile/lib/utils/image_url_builder.dart

@@ -0,0 +1,16 @@
+import 'package:hive/hive.dart';
+import 'package:openapi/api.dart';
+
+import '../constants/hive_box.dart';
+
+String getThumbnailUrl(final AssetResponseDto asset,
+    {ThumbnailFormat type = ThumbnailFormat.WEBP}) {
+  final box = Hive.box(userInfoBox);
+
+  return '${box.get(serverEndpointKey)}/asset/thumbnail/${asset.id}?format=${type.value}';
+}
+
+String getImageUrl(final AssetResponseDto asset) {
+  final box = Hive.box(userInfoBox);
+  return '${box.get(serverEndpointKey)}/asset/file?aid=${asset.deviceAssetId}&did=${asset.deviceId}&isThumb=false';
+}