Fix MP4 parser issue in reading length of URL array from esds boxes.

As per MP4 spec, the length of URL array is a 8 bit number.

#minor-release

PiperOrigin-RevId: 458421436

libraries/extractor/src/main/java/androidx/media3/extractor/mp4/AtomParsers.java

@@ -1659,7 +1659,7 @@ import org.checkerframework.checker.nullness.compatqual.NullableType;
       parent.skipBytes(2);
     }
     if ((flags & 0x40 /* URL_Flag */) != 0) {
-      parent.skipBytes(parent.readUnsignedShort());
+      parent.skipBytes(parent.readUnsignedByte());
     }
     if ((flags & 0x20 /* OCRstreamFlag */) != 0) {
       parent.skipBytes(2);