Additional Region Support for select locales

[rgeraghty]

Provide a general summary of the feature here

We would like to support some additional locales for region support, in same way as exists for French (Canada)

Meaning....

• Only added regional support, no new translations required

Example...

• French Canadian
  • In case of French (Canada) we display translations using fr-FR (French France), but use region of Canada.

New locales requested...

• es-419 (Spanish, Latin America)
• es-MS (Spanish, Mexico)
• en-AU (English, Australian)
• en-IL (English, Israel)

🤔 Expected Behavior?

• es-419: displays es-ES translations, but uses es-419 region
• es-MX: displays es-MX translations, but uses es-MX region
• en-AU: display en-US translations, but uses en-AU region
• en-IL: display en-US translations, but uses en-IL region

However, if intl string files added for any of the above, at later stage, then use matching strings files (eg: en-AU string files + region). Looking at current code seems already supported, just need the locales list updated for above,

😯 Current Behavior

These will all revert to en-US only

💁 Possible Solution

From looking at the code, looks like it might be just updating language tables:
https://github.com/adobe/react-spectrum/blob/main/.chromatic-fc/constants.js
https://github.com/adobe/react-spectrum/blob/main/packages/dev/docs/pages/react-aria/home/I18n.tsx
https://github.com/adobe/react-spectrum/blob/main/packages/%40internationalized/message/src/MessageDictionary.ts
https://github.com/adobe/react-spectrum/blob/main/packages/%40internationalized/string/src/LocalizedStringDictionary.ts

and some related files like storybook and tests:
https://github.com/adobe/react-spectrum/blob/main/.storybook/constants.js
https://github.com/adobe/react-spectrum/blob/main/.storybook-s2/constants.js
https://github.com/adobe/react-spectrum/blob/main/packages/%40internationalized/date/tests/DateFormatter.test.js
https://github.com/adobe/react-spectrum/blob/main/packages/%40internationalized/date/tests/queries.test.js

MessageDictinary looks to already support this functionality, with just adding language codes to support. es-419 might need extra handling as not xx-XX format.

🔦 Context

Match other Adobe areas (pls contact rgeraght, lreis any question)

💻 Examples

No response

🧢 Your Company/Team

Adobe

🕷 Tracking Issue

No response

[dannify]

Should en-AU: display en-GB translations, but use en-AU region?? @rgeraghty

[rgeraghty]

@dannify en-AU would fall back to en-US strings (as no en-AU strings present, like en-GB falls back to en-US) but use the en-AU region (https://github.com/adobe/react-spectrum/blob/main/packages/%40internationalized/message/src/MessageDictionary.ts#L59)

We have option at any time to add strings for en-AU, en-GB, fr-CA, es-MX etc.... if feel its needed, but not required for this this issue request, which is just add additional locales to current lang supported list, to get the region support.

I updated expected behaviour (just now) in issue description to add note for this,