Ruleset testing

As per https://github.com/everywall/ladder-rules/pull/3, we'll need to implement some robust testing.

The main challenge is to test after client-side JS rendering happens, which will probably mean we'll need a headless browser.

A test could look like this: https://github.com/everywall/ladder/blob/ladder_tests/tests/tests/www-wellandtribune-ca.spec.ts

And the results like this.

Perhaps we'll need some codegen in order to go from ruleset to test?