Fix OpenAI realtime mode doesn't work with Simli

[Antonyesk601]

Please describe the changes in your PR. If it is addressing an issue, please reference that as well.

OpenAI realtime depended on getting a BotStoppedSpeaking upstream frame which never got sent because Simli-Client was creating TTSAudioRawFrame objects even when the avatar is silent,
You can reproduce the bug which this fix solved by adding a SimliVideoService component to OpenAI foundational example
Sample SimliVideoService

simli = SimliVideoService(
            SimliConfig(
                apiKey=os.getenv("SIMLI_API_KEY"),  # API Key
                faceId=os.getenv("SIMLI_FACE_ID"),  # Face ID
                syncAudio=True,
                handleSilence=True,
                maxSessionLength=900,
                maxIdleTime=30,
            ),
            latency_interval=0,
            use_turn_server=False,
        )