Drop unsupported language switching commands for OneCore (#13779)
Fixes #13732
Summary of the issue:
OneCore keeps a cache of voices for NVDA in the registry.
OneCore fails to automatic language switch when remnants of a previously installed OneCore language exist in the cache.
This causes speech to not be announced.
This is only an issue for installed copies, as portable copies bypass the NVDA OneCore cache.
Description of how this pull request fixes the issue:
Drop the language change command if a given language is unsupported by OneCore.
