StoreBroker does not prevent use of unsupported language codes

[riverar]

After some exhausting troubleshooting of the Ingestion API, I discovered my app was attempting to provide a listing for bs-BA (Bosnia and Herzegovina). According to the List of supported languages, this is not a supported language code (as-is).

https://learn.microsoft.com/windows/apps/publish/publish-your-app/supported-languages?pivots=store-installer-msix#list-of-supported-languages

Opinions:

• Ingest API should throw an appropriate error when this occurs (instead of a blanket 500 internal error)
• StoreBroker should throw an appropriate error (or warn the user) when this input is detected