Add AVIF special case to ThumbnailUtils

Similar to HEIC, AVIF files can also have smaller thumbnail images
along with the main image in the container. So try to fetch that
first instead of decoding the main image when creating a thumbnail.

Test: ThumbnailUtils test still pass (with the new AVIF test).
Bug: 141654151
Change-Id: I74afffe0e180edd425154daad30e07fcb0781ee6

media/java/android/media/ThumbnailUtils.java

@@ -272,7 +272,8 @@ public class ThumbnailUtils {
         if (mimeType.equals("image/heif")
                 || mimeType.equals("image/heif-sequence")
                 || mimeType.equals("image/heic")
-                || mimeType.equals("image/heic-sequence")) {
+                || mimeType.equals("image/heic-sequence")
+                || mimeType.equals("image/avif")) {
             try (MediaMetadataRetriever retriever = new MediaMetadataRetriever()) {
                 retriever.setDataSource(file.getAbsolutePath());
                 bitmap = retriever.getThumbnailImageAtIndex(-1,