Inline test.purs / test.js files

[thumphries]

I've noticed we have a few inline test.purs and test.js files lying around, and these are currently picked up and thrown into main.js.

I assume we'll want to either stop doing this (moving all tests into a known test directory somewhere) or settle on a naming convention. Including in main.js is the worst possible outcome (short of not compiling them at all)

[thumphries]

@charleso needs to be solved before we flip the switch