proxy dns with NOTIMP error

[rp-hello]

Chromium will send SVCB/HTTPS type dns query, which cause dns leak.

To prvent dns leak,

• If the dns query type is not implemented, should return NOTIMP error, not just send data to original destination.
• If the dns query has wrong format domain, should return FORMERR error, not send data to original destination.

Copy from #2595

[rp-hello]

Here is similar issue XTLS/Xray-core#3006.
Could we just introduce nonIPQuery option?

• when nonIPQuery=drop, just return NOTIMP, and this is default behavior
• when nonIPQuery=skip, follow the original chain, call connWriter.WriteMessage

[github-actions]

It has been open 120 days with no activity. Remove stale label or comment or this will be closed in 5 days

[xiaokangwang]

I think it would be better if we guard this new behavior behind a flag or option, otherwise it would take significantly longer time decide if a regression is justified.