Adds in default Intl.DateTimeFormat

[TatianaKapos]

Description

Adds in a basic Intl.DateTimeFormat, see https://tc39.es/ecma402/#datetimeformat-objects. This DateTimeFormat has all the options but dayPeriod and more work is required to fully meet ECMA402 specification.

Takes a lot of code/functions/styling from apples current implementation (https://github.com/facebook/hermes/blob/main/lib/Platform/Intl/PlatformIntlApple.mm) and added them into a shared code file. You also won't get this change by default, you'll still need to set the HERMES_ENABLE_INTL flag to ON.

Reason for Change

See #87. TDLR: start of work to adding windows support for the Intl APIs. Android already supports the Intl APIs while Apple has starting filling out their own implementation (facebook@150bf0e and beyond). We should follow suit as Hermes becomes the default engine for RNW and has already been asks for it.

Further work need to match ECMA402 specifications

• Implementation needed for DateTimeFormat.formatToParts
• Add support for dayPeriod Option
• Add testing and validation for incorrect input

Testing

Unit Tests included in PR and passing. Expected output matching when plugged into https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat

Current Status of test262.js files, since we only have DateTimeFormat implemented, I would expect a lot of these tests to fail

Microsoft Reviewers: Open in CodeFlow

[vmoroz]

@TatianaKapos, just FYI: I had fixed the CodeFlow link in the description.

[mganandraj]