[3/N][refactor] refactoer quantization (#2504)

### What this PR does / why we need it?
Move torchair related qunatization section into torchair dir to make the
code clear. Next step we'll remove all torchair related code outside of
torchair quantization.

### Does this PR introduce _any_ user-facing change?
NO

### How was this patch tested?
vLLM version: main
vLLM main:
ab9f2cfd19


- vLLM version: v0.10.1.1
- vLLM main:
959783fb99

Signed-off-by: hust17yixuan <303660421@qq.com>

vllm_ascend/torchair/torchair_model_runner.py

@@ -38,6 +38,7 @@ from vllm_ascend.torchair.utils import (TorchairCommonAttentionMetadata,
                                         check_torchair_cache_exist,
                                         converting_weight_acl_format,
                                         register_torchair_model,
+                                        torchair_quant_method_register,
                                         write_kv_cache_bytes_to_file)
 from vllm_ascend.utils import (ACL_FORMAT_FRACTAL_ND, ACL_FORMAT_FRACTAL_NZ,
                                is_310p)
@@ -67,6 +68,7 @@ class NPUTorchairModelRunner(NPUModelRunner):
 
         self._check_batch_sizes_consistency()
         register_torchair_model()
+        torchair_quant_method_register()
 
     def _get_forward_metadata_across_dp_and_pad(
             self, num_tokens: int, with_prefill: bool, enable_dbo: bool