test(format/html): add prettier tests

[dyc3]

Summary

This imports all the HTML tests from prettier into our snapshot tests. It excludes some tests that rely on prettier's infra (eg. the "cursor" tests). At the time of writing, only 4 of prettier's tests outright fail, and a large portion of the imported tests don't match prettier's output.

Caution

This PR is stacked on the following PRs. Do not merge it without merging the others and rebasing this branch. To review this PR, look at the last commit only.

• fix(format/html): fix long content failing to print if element has <= 1 attributes #5055

Test Plan

CI should pass except for the 4 tests mentioned above.

[codspeed-hq]

CodSpeed Performance Report

Merging #5056 will not alter performance

_{Comparing html-add-prettier-tests (90d257b) with next (56527db)}

Summary

✅ 94 untouched benchmarks

[dyc3]

Regarding the failing tests:

• specs::prettier::html::prettier_ignore::issue_15738_html is for handling the (extremely old, deprecated) special <plaintext> tag, where all the content after it is treated as plain text. https://developer.mozilla.org/en-US/docs/Web/HTML/Element/plaintext -- I don't think it's worth the time and effort to support this tag, especially because it's deprecated and removed from web standards.
• specs::prettier::html::prettier_ignore::unclosed_html and specs::prettier::html::prettier_ignore::unclosed2_html deal with unclosed tags, and test for prettier's ability to not add closing tags when they aren't present in the presence of a prettier ignore comment (requires parser changes)
• specs::prettier::html::basics::broken_html_html would (probably) also be fixed when the unclosed tests are fixed

[dyc3]

I've removed the 4 failing tests temporarily because I would rather get these in the repo to help avoid regressions in future PRs, and the underlying issue preventing me from fixing them requires some closer examination.