Add CP_UTF8 support to GetConsoleLangId

[lhecker]

For discussion!
Relevant context, if you're curious (search for "dragons"): MSFT-56188683

[DHowett]

Wow, this one is intricate for how simple the code looks

[miniksa]

The only question I really have is "what happens to FormatMessage calls inside a client process on the other end when you return this?"

I fully believe that.... 10 years ago... I didn't think through that it would make sense for UTF-8... which had never really been supported in the past... to return the STATUS_NOT_SUPPORTED. But I'm also wondering whether FormatMessage is now gonna be broken and other less enlightened tools are going to have a really bad time.

[lhecker]

I'll of course test this properly before we merge this, but in theory when this returns the unsupported status, the per-thread locale will remain undefined. In that case FormatMessage is documented to use the user locale. So theoretically it should just use Japanese or whatever, as expected, and just how it behaves in non-East-Asian locales.