test(web-test-runner): run hydration tests in CI @W-18780671

[wjhsf]

Details

Another step of our migration to web-test-runner. Hydration tests are even more annoyingly convoluted than the basic integration tests. First, the component code is bundled into an IIFE and executed in a vm.Script to get the server-side generated markup. Then that, the client-side component code, and test config are wrapped in a generated test function. I've moved some of it to ESM imports, but getting rid of all of the IIFEs means using the experimental vm.Module. (Which will be fine, just more effort, so this PR is a checkpoint.)

Also, apparently this has been broken for a while:

import { setHooks, sanitizeHtmlContent } from "@lwc/ssr-runtime";
setHooks({ sanitizeHtmlContent: (v) => v.toUpperCase() });
sanitizeHtmlContent("foo"); // Error: sanitizeHtmlContent hook must be implemented.

I believe this is because sanitizeHtmlContent was being directly exported. Changing that to a wrapper function and updating a non-exported variable fixed the problem.

Lastly, this also includes some cleaning up of the helper files because they were just a littered dumping ground of utilities.

Does this pull request introduce a breaking change?

• 😮‍💨 No, it does not introduce a breaking change.
• 💔 Yes, it does introduce a breaking change.

Does this pull request introduce an observable change?

• 🤞 No, it does not introduce an observable change.
• 🔬 Yes, it does include an observable change.

GUS work item

[wjhsf]

Just moved to a new file.

[wjhsf]

Just moved to a new file.

[wjhsf]

Just moved to a new file.

[wjhsf]

Largely copied from the karma version, with some rekerjiggering.

[wjhsf]

Largely copied from the karma version.