Initial replacement for Star Ocean's stencil upload

Obviously, it's pretty darn inefficient right now, although it seems perfectly fast on desktop.  I wanted to make sure we had a starting place to optimize, though.

Improves #1392 (probably not fast enough on mobile.)  Intentionally made it so disabling stencil test disables this upload too, and it's unplayable with stencil testing + no stencil upload anyway.

-[Unknown]