Paint in place for real

[Gaurav0]

I am not super familiar (or familiar at all) with this WebGL stuff but basically it goes like this:

• Select one of the parts we are going to be recoloring dinamically (for now only the pieces that are tied to the body color as they seem to be using the same palette)
• Create a canvas with a webgl context (shared - expensive operation performed once)
• Initialize a recolor cache
• Download the base variant for the asset (light)
• Apply recolor in the webgl canvas.
• Copy to an output webgl canvas so we can reuse the shared one for the next drawing.
• Copy to a 2D context canvas we have offscreen. This is then copied once again to the preview canvas, and is the one used for downloads and stuff.

With CPU pixel by pixel it takes 190ms-230ms. With GPU it takes around 90ms-130ms.
The improvements are there and seem to be working. I may not be using the optimal setup tho.

[Gaurav0]

I'm not sure why this didn't deploy automatically.

Deployed to https://paint-in-place-for-real--liberatedpixelcup.netlify.app/

[cdvv7788]

@Gaurav0 @jrconway3 I am done for now with this PR. I will need more details for other recolors, but there are a bunch of items being drawn on the fly now.
It may be a good idea to have someone else try to add the next palette (there is a document for that) to see if it is understandable and easy to follow along.
Awaiting approvals to move on to the next big thing I want to try: A component to pick/make palettes on the fly. If I succeed, the variants can be presented in different ways, and we can reduce the tree clutter. We will see :).

[Gaurav0]

Closing in favor of #284