McUsd test asset doesn't render correctly in the three.js Hydra delegate

[hybridherbst]

See https://usd-viewer.glitch.me/?file=https%3A%2F%2Fraw.githubusercontent.com%2Fusd-wg%2Fassets%2Fmain%2Ffull_assets%2FMcUsd%2FMcUsd.usdz

• colors look off (still some colorspace problem?)
• transparency/cutout doesn't work
• many things are shiny but probably shouldn't

usdview reference:

[beersandrew]

@hybridherbst i think this can be closed