feat(mobile): platform image providers (#20927)

* platform image providers

* use key

* fix cache manager

* more logs, cancel on dispose instead

* split into separate files

* fix saving to cache

* cancel multi-stage provider

* refactored `getInitialImage`

* only wait for disposal for full images

* cached image works

* formatting

* lower asset viewer ram usage

---------

Co-authored-by: Alex <alex.tran1502@gmail.com>

mobile/lib/infrastructure/loaders/thumbhash_image_request.dart

@@ -0,0 +1,25 @@
+part of 'image_request.dart';
+
+class ThumbhashImageRequest extends ImageRequest {
+  final String thumbhash;
+
+  ThumbhashImageRequest({required this.thumbhash});
+
+  @override
+  Future<ImageInfo?> load(ImageDecoderCallback decode, {double scale = 1.0}) async {
+    if (_isCancelled) {
+      return null;
+    }
+
+    final Map<String, int> info = await thumbnailApi.getThumbhash(thumbhash);
+    final frame = await _fromPlatformImage(info);
+    return frame == null ? null : ImageInfo(image: frame.image, scale: scale);
+  }
+
+  @override
+  void _onCancelled() {
+    if (!kReleaseMode) {
+      debugPrint('Thumbhash request $requestId for $thumbhash was cancelled');
+    }
+  }
+}