CurrentRanger OLED support shell

The [Current ranger](https://lowpowerlab.com/shop/product/152) is currently the only game in town for hobbyist-grade low-current measurement. It has an optional OLED display that is much too fragile for my tastes, though, as supplied - both the screen itself and the 4-pin mount. This wraps a shell around the screen that is a little taller than the glass, and supports it against the board. The notches allow nonviolent extraction.

Fusion 360: https://a360.co/2F8gukr

In full disclosure:
* this works well with the printed case with recent kits; it probably wouldn't work well with the injection-molded case that recesses the board lower.
* the pins weren't quite right in my print, still - just a little too fat or just a little misaligned. I broke them off and it fits pretty well; they aren't really necessary. OLED boards can vary in their hole positions; customize to yours, or just break them out.
* white is not the best color. it's what I had loaded and I didn't expect this p