Open AI completions integration

[nalbion]

Proposal

User says "chat/completion mode" (or "command mode" to exit) and tool window appears with for editing dictated commands, with option to auto submit.

The isSupported() method of most IntentResolver classes would return false if NlpContext indicated chat or completion mode.

(A new NlpContext is currently created in ExecuteVoiceCommandAction, I'm not sure if this is the best design possible though).

see also - https://platform.openai.com/docs/guides/completion/prompt-design