[ModelLoader][Feature] Add rfork support for fast model loading (#7392)

### What this PR does / why we need it?
Support an new load format: RFORK

For implementation details of this feature, please refer to #7441


### Does this PR introduce _any_ user-facing change?

add an new options for load-format: rfork

e.g.
```bash
vllm serve /workspace/models/Qwen3-8B --load-format rfork
```

### How was this patch tested?

- vLLM version: v0.17.0
- vLLM main:
4034c3d32e

Signed-off-by: Marck <1412354149@qq.com>

vllm_ascend/__init__.py

@@ -30,8 +30,10 @@ def register_connector():
 
 def register_model_loader():
     from .model_loader.netloader import register_netloader
+    from .model_loader.rfork import register_rforkloader
 
     register_netloader()
+    register_rforkloader()
 
 
 def register_service_profiling():