split testsuite into files

[6293]

#21
asking for your review @untitaker before migrating rest of the testcases

[untitaker]

I think it would be more convenient to embed lhs and rhs into the same file like so:

{
    "lhs": { ... },
    "rhs": { ... }
}

Other than that it looks good to me. I also just learned about insta's glob last night.

[untitaker]

this is good but github actions is having an incident. i assume that's why the lint job does not run right now

[untitaker]

excellent, ty!