Add Volcengine support for TTS and ASR services

- Introduced Volcengine as a new provider for both TTS and ASR services.
- Updated configuration files to include Volcengine-specific parameters such as app_id, resource_id, and uid.
- Enhanced the ASR service to support streaming mode with Volcengine's API.
- Modified existing tests to validate the integration of Volcengine services.
- Updated documentation to reflect the addition of Volcengine as a supported provider for TTS and ASR.
- Refactored service factory to accommodate Volcengine alongside existing providers.

engine/providers/asr/__init__.py

@@ -3,6 +3,7 @@
 from providers.asr.buffered import BufferedASRService, MockASRService
 from providers.asr.dashscope import DashScopeRealtimeASRService
 from providers.asr.openai_compatible import OpenAICompatibleASRService, SiliconFlowASRService
+from providers.asr.volcengine import VolcengineRealtimeASRService
 
 __all__ = [
     "BufferedASRService",
@@ -10,4 +11,5 @@ __all__ = [
     "DashScopeRealtimeASRService",
     "OpenAICompatibleASRService",
     "SiliconFlowASRService",
+    "VolcengineRealtimeASRService",
 ]