Chore: AssemblyAI add dynamic keyterms + return language code + normalize preemptive generation validation

[dan-ince-aai]

Hi team!

Added dynamic keyterms updating without closing the stream, sends a message with type "UpdateConfiguration" https://www.assemblyai.com/docs/api-reference/streaming-api/streaming-api#send.sendUpdateConfiguration

Language code is returned when "Language_detection" is True (set now by default), and we pass this in the preflight and final transcripts, its only returned with utterances so we store it when we get it https://www.assemblyai.com/docs/api-reference/streaming-api/streaming-api#receive.receiveTurn.language_code

Also normalized the preemptive generation text in agent_activity before validation, so we only compare if there are new words and not any changes in casing or punctuation.

[dan-ince-aai]

Hi @longcw @theomonnom may we have this updated PR reviewed?

The type checks and tests are failing due to OpenAI plugin