Initial vLLM-omni repository structure

- Add complete directory structure for multimodal and non-autoregressive processing
- Include AsyncLLM, OmniEngine, and DiffusionEngine modules
- Add processors, schedulers, executors, and output processors
- Add API interfaces for Higress, Gradio, and ComfyUI
- Add configuration management and CLI interface
- Add comprehensive test structure and documentation
- Add pyproject.toml with dependencies and project configuration
- Add examples and documentation structure

tests/__init__.py

@@ -0,0 +1,5 @@
+"""
+Test suite for vLLM-omni.
+
+This package contains unit tests, integration tests, and benchmarks for vLLM-omni.
+"""