Add a fail-fast check in `ExoPlayerImpl` to ensure the equality of the lengths of `ShuffleOrder` and the current playlist. Also improve the documentation of `setShuffleOrder(ShuffleOrder)` with explicit instruction on this.
Issue: androidx/media#480
#minor-release
PiperOrigin-RevId: 544009359
(cherry picked from commit 9cabbc9badbc9301f5e13398b8444377c4e72543)
