Reland "quantize: use scan_order instead of passing scan/iscan"

Reland "quantize: use scan_order instead of passing scan/iscan"

This is a reland of commit 14fc40040ff30486c45111056db44ee18590a24a

Parent change fixed in crrev.com/c/webm/libvpx/+/4305500

Original change's description:
> quantize: use scan_order instead of passing scan/iscan
>
> further reduces the arguments for the 32x32. This will be applied to the base
> version as well.
>
> Change-Id: I25a162b5248b14af53d9e20c6a7fa2a77028a6d1

Change-Id: I2a7654558eaddd68bd09336bf317b297f18559d2