test: Add tests for live streaming configs

This PR extends the existing Streaming tests to consider new configurations that have been added, including:

- `output_audio_transcription`
- `input_audio_transcription`
- `realtime_input_config`
- `enable_affective_dialog`
- `proactivity`

These configurations are tested individually and also combined, to cover all the possibilities, increasing the testing coverage and ensuring everything is working as expected.

In addition, the new configuration values are also validated to be sure they are properly initialized.

PiperOrigin-RevId: 780178334

Author: hangfei