Add method to set model information

[MasterOdin]

This should use the new command structure for:

• transcript.command.switch_model: {"channel_idx": number|null, "model": "broad"|"narrow"}
• transcript.command.switch_language_model: {"channel_idx": number|null, "language_model": string}
• transcript.command.switch_acoustic_model: {"channel_idx": number|null, "acoustic_model": string}