Rewrite dateTime.js to use current localeData

[bearfriend]

GAUD-9717: Rewrite intl/common and intl/dateTime to use contained data sets per locale

Run #1

• Use new locale-data/
• Do not modify tests

644 failed tests

Run #2

• Refactor tests so they properly set the language between tests, including waiting for locale data to load
• Fix documentLocaleSettings reset method so it runs listeners when it "resets" (changes) the language back to English. This is only used in tests.
• Rename locale-data/ to match the CLDR source names and update how the files are matched for loading

304 failed tests

Run #3

• Update tests with appropriate whitespace (no-break-space, rtl-mark etc.) to match new locale data. These changes will only improve UX without being disruptive.

242 failed tests

Run #4

• Be more forgiving when relying on separators to parse dates and date formats since they may contain invisible whitespace (e.g. rtl-mark)
• Support unicode symbols without a .NET equivalent
  • LLLL - Stand-alone month in year (e.g. Catalan: MMMM -> "d'abril", LLLL -> "abril")
  • cccc - Stand-alone day of week
  • K - Hour in day, 12 hour, 0-11 (e.g. "0:29 pm")

225 failed tests

Run #5

• Downgrade locale-data/ files to maintain existing time formats (minus whitespace improvements and legitimate bugs)
• Where CLDR is wrong (ko), add overrides files and rework how they are applied

102 test failures

Run #6

• Downgrade locale-data/ files to maintain existing date formats (minus whitespace improvements and legitimate bugs)
• Align pt and pt-BR

0 failed tests

[dlockhart]

These were just mistakes you noticed?

[bearfriend]

"Mistakes" AI noticed, but I don't trust it understands the context. I'll make a story to review these, but will revert these from this PR.

[dlockhart]

This stuff ends up all being static eh? Wonder if it'd be useful doing these calculations at build-time instead of runtime and storing them in locale-data.js?

[bearfriend]

I'll look at this, but it's cached after the first run. I do want to avoid storing converted data in locale-data/ so we just have a clean source of truth. A lot of this may go away very soon too with the skeleton work coming up, so we can look at it again then.

[bearfriend]

A promise that can be overwritten each time the locale changes

[bearfriend]

Since we can't Object.freeze the shared object (so we can update its properties), we proxy it and disallow (re)defining and deleting properties outside this module.

[bearfriend]

Make localeDataTarget thenable, always redirecting to the dynamic localeDataPromise. We use defineProperty here mostly to prevent enumerability. i.e. before first resolution, Object.keys(localeData) // -> []

This means localeData acts as its own promise, and allows existing and future intl functions like formatDate to remain synchronous, as long as there is a top-level await localeData anywhere before they can be called, which we already do right at the end of this module. Shifting that responsibility to consumers is an option that would prevent blocking while the initial locale data loads, but in practical terms would offer little to no benefit as something else is likely to be imported that already top-level awaits it. After that, any consumer is responsible for managing updates:

// library
import { localeData } from '@brightspace-ui/intl/lib/locale-data/current.js';
import { resolveSupportedLocale } from '@brightspace-ui/intl/lib/locale-data/supported.js';

// current.js already awaited the initial locale's data
export function getMonths(format) {
	const months = localeData.months.standAlone[format];
}

export async function changeLanguage(lang) {
	document.documentElement.lang = resolveSupportedLocale(lang);
	await localeData;
}

// component/mixin
...
import { localeData } from '@brightspace-ui/intl/lib/locale-data/current.js';

class MyComponent ... {
	...
	connectedCallback() {
		this.connectedCallback();
		this.addEventListener('d2l-locale-data-change', () => requestUpdate('localeData'));
	}

	render() {
		return html`
			<ul>${localeData.months.standAlone.wide.map(m => html`
				<li>${m}</li>`)}
			</ul>
		`;
	}
}

[bearfriend]

Update the double proxied promise pointer

[bearfriend]

The proxy already prevents consumers adding new properties, but this ensures we aren't adding extraneous properties when we change locales. We can probably remove this in favor of more tests once generating/modifying the locale data files is more settled down, but for now it's useful to catch inconsistencies there.

[bearfriend]

Prevents accidental/attempted overwriting of localeData subproperties since without this they would be direct references. We can't use structuredClone yet. Thanks Safari!