This MR allows existing some existing Windows TTS Engines, such as Amazon Polly, to be used in Far Cry 6, and possibly in other games/applications.
-- v2: sapi: Implement ISpVoice::WaitUntilDone. sapi: Implement ISpTTSEngineSite::GetActions/Rate/Volume. sapi: Implement ISpTTSEngineSite::Write.