Reorder canvaskit demos, add fixed 3d cube demo

Change-Id: I53ae7bec8470ac80c56780280a7d08974afdc35a
No-Try: true
Docs-Preview: https://skia.org/?cl=289784
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/289784
Commit-Queue: Nathaniel Nifong <nifong@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
1 file changed