Make the app a web app

Would be much better that way, but it would require some significant changes and abstractions. For example, we couldn't use the `module` module, like we do [here](https://github.com/kentcdodds/slice-js/blob/1599643fd384c1699f5c82c834656c5ba54ad1c0/src/slice-code/test/helpers/utils.js#L164). We definitely still need to use the `module` module for the unit tests we have, but for the browser side of things we'd have to use `eval`.

I'm thinking that the `test/helpers/utils.js` file could use some refactoring and breaking up into smaller pieces.

Start with test/helpers/utils.js, especially the linked helper usage, and compare its unit-test needs with the browser-side requirement described in the issue. Before implementation, define the browser app boundary and how unit tests remain supported; the issue currently does not specify a concrete completion criterion.

Written by the indexing model from the issue text.