Make helpers configurable in setupGlobalA11yHooks mode

[jgwhite]

This adds an additional argument, options, to setupGlobalA11yHooks which allows us to specify additional helpers to hook into.

import {
  setupGlobalA11yHooks,
  DEFAULT_A11Y_TEST_HELPER_NAMES,
} from 'ember-a11y-testing/test-support';

setupGlobalA11yHooks(() => true, {
  helpers: [...DEFAULT_A11Y_TEST_HELPER_NAMES, 'render', 'tab'],
});

The motivating use case is to automatically perform an audit when the render helper is used, thereby improving automated coverage for component tests.

[drewlee]

This would be a breaking change IMO, in that we'd be introducing a new point for a test to fail where one didn't exist before. There are also perf considerations, in that the total volume of a11y audits would substantially increase.

I'm wondering if instead we could make this an opt-in setting, or expose an API to make global hook registration configurable, as this project isn't quite ready for a v5 release. I'm curious to get @scalvert's take, as he authored the hooks implementation, and I'm sure there was a good reason why we didn't leverage render.

[MelSumner]

@drewlee I think even if we consider this a breaking change AND decide that it should be an option, the option should be to turn it off (having it on should be the default state). WDYT?

[scalvert]

I really like this idea for a few reasons:

1. It fills the gap nicely for rendering tests so we have a complement to the application tests that invoke visit
2. It provides a tiered set of APIs that cover more test use cases

I also like what you suggested, @MelSumner, WRT to making this an option. What if we, in fact, made all of the hook bindings optional, with specific defaults. This would allow us to add this change, keep the current set of defaults, and give folks a path to using render in addition to those defaults. The next major we could then fold render into that default set, which would be a natural time for it to graduate.

Thoughts?

[jgwhite]

Thanks for the splendid feedback and ideas y'all. I'll continue working on it this week.

[jgwhite]

@gregone and I addressed all the feedback and added the new configuration option in the most pragmatic way possible. Looking forward to hearing what y’all think.