Test scripts:

  Script            Compiler host   Output host/VM
- this.bqn          Any
- js                Self-host       Javascript
- dz_comp           dzaima/BQN      dzaima/BQN
- dz_wasm.js        dzaima/BQN      WebAssembly

this.bqn can be run in any implementation that supports the necessary
system functions (•file.List, •file.Lines, •args, •Out, •BQN, •Repr). It
runs all tests by default, and can be run on a subset by passing their
names as arguments.

dz_comp uses the self-hosted compiler ../src/c.bqn by default but not
the runtime ../src/r*.bqn. Pass -rt to test with the runtime, and -nocomp
to test dzaima/BQN only (this doesn't pass as of the time of writing).

Test cases (cases/):
                  js    dz_comp   dz_wasm.js
- simple.bqn       *       *          *
- syntax.bqn       *       *
- prim.bqn                 *

js or dz_comp can be run on a specified set of tests by passing the test
names as arguments.