webgpu support for qwen3.5 (#27996)
webgpu support for qwen3.5, adding LinearAttention and
CausalConvWithState ops based on this proposal:
from https://github.com/onnx/onnx/pull/7767
The model can be created with model builder from
https://github.com/microsoft/onnxruntime-genai/blob/main/src/python/py/models/builder.py.
For example for the text only flavor:
```
python builder.py -m Qwen/Qwen3.5-0.8B -o Qwen3.5-0.8B -e webgpu -p int4 --extra_options int4_accuracy_level=4 exclude_embeds=False
```
