[Feat] Unquantized Linear to nz and control all nz-cast (#3356)

### What this PR does / why we need it?
Currently, when executing to the Linear layer of models in vLLM-Ascend,
the weights format is ND in unquantized case and skipped ascend case.
This PR supplements the execution logic for Linear layer. We use a new
global variable: VLLM_ASCEND_ENABLE_NZ. When VLLM_ASCEND_ENABLE_NZ=1 and
CANN version is 8.3, the weights of the Linear layer will be converted
to FRACTAL_NZ, in both unquantized case and skipped ascend case. We also
use VLLM_ASCEND_ENABLE_NZ to control the existing NZ conversion, such as
w8a8-quantized case.

### Does this PR introduce _any_ user-facing change?
Add a new global variable VLLM_ASCEND_ENABLE_NZ. If you want to use NZ
format, you should set VLLM_ASCEND_ENABLE_NZ=1.

### How was this patch tested?

- vLLM version: v0.11.0rc3
- vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.0

Signed-off-by: anon189Ty <Stari_Falcon@outlook.com>

tests/ut/quantization/test_quant_config.py

@@ -4,10 +4,10 @@ import torch
 from vllm.attention.layer import Attention
 from vllm.model_executor.layers.fused_moe import FusedMoE
 from vllm.model_executor.layers.fused_moe.config import FusedMoEConfig
-from vllm.model_executor.layers.linear import (LinearBase,
-                                               UnquantizedLinearMethod)
+from vllm.model_executor.layers.linear import LinearBase
 
 from tests.ut.base import TestBase
+from vllm_ascend.ops.linear import AscendUnquantizedLinearMethod
 from vllm_ascend.quantization.quant_config import (AscendKVCacheMethod,
                                                    AscendQuantConfig)
 from vllm_ascend.utils import ASCEND_QUANTIZATION_METHOD
@@ -82,7 +82,7 @@ class TestAscendQuantConfig(TestBase):
                           'is_layer_skipped_ascend',
                           return_value=True):
             method = self.ascend_config.get_quant_method(linear_layer, ".attn")
-            self.assertIsInstance(method, UnquantizedLinearMethod)
+            self.assertIsInstance(method, AscendUnquantizedLinearMethod)
 
         # Test quantized layer
         with patch.object(self.ascend_config, 'is_layer_skipped_ascend', return_value=False), \