[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>

vllm_ascend/envs.py

@@ -169,6 +169,9 @@ env_variables: Dict[str, Callable[[], Any]] = {
     lambda: int(os.getenv("VLLM_ASCEND_KVCACHE_DELAY_FREE_TIMEOUT", 250)),
     "VLLM_ASCEND_ENABLE_MLAPO":
     lambda: bool(int(os.getenv("VLLM_ASCEND_ENABLE_MLAPO", '0'))),
+    # Whether to enable transpose weight and cast format to FRACTAL_NZ.
+    "VLLM_ASCEND_ENABLE_NZ":
+    lambda: int(os.getenv("VLLM_ASCEND_ENABLE_NZ", 1)),
 }
 
 # end-env-vars-definition