[Feat.]: 310p support MOE models (#6530)

### What this PR does / why we need it?
This pull request integrates comprehensive support for Mixture of
Experts (MoE) models on the Ascend 310P device within the vllm-ascend
framework. It achieves this by introducing specialized modules for
expert selection, fused MoE layers, and optimized all-gather
communication. The changes also refine existing NPU operations, making
them more consistent and efficient for 310P, ultimately enhancing the
performance and compatibility of MoE models on this hardware.

Highlights
310P MoE Support: Introduces dedicated implementations for Mixture of
Experts (MoE) models on Ascend 310P devices, including new modules for
expert selection, fused MoE layers, and communication.
All-Gather Communication: Enforces the use of ALLGATHER communication
for MoE operations on 310P, optimizing data transfer and leveraging
NPU-specific token dispatching.
Simplified NPU Operations: Removes conditional type casting for
npu_swiglu and enables custom rotary embedding kernels unconditionally,
suggesting improved native support for 310P.
New MoE Classes Registered: Registers AscendFusedMoE310 and
AscendSharedFusedMoE310 to integrate 310P-specific MoE layers into the
system's custom operation registry.

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

### How was this patch tested?
offline test and server test, with qwen3-30b-a3b,tp/ep 4 on 310p

- vLLM version: v0.15.0
- vLLM main: https://github.com/vllm-project/vllm/commit/v0.15.0

---------

Signed-off-by: pu-zhe <zpuaa@outlook.com>

vllm_ascend/utils.py

@@ -625,6 +625,7 @@ def register_ascend_customop(vllm_config: VllmConfig | None = None):
 
     # 310P: override selected ops with 310P implementations (keep minimal changes outside _310p)
     if is_310p():
+        from vllm_ascend._310p.fused_moe.fused_moe import AscendFusedMoE310, AscendSharedFusedMoE310
         from vllm_ascend._310p.ops.activation import AscendSiluAndMul310
         from vllm_ascend._310p.ops.layernorm import AscendGemmaRMSNorm310, AscendRMSNorm310
         from vllm_ascend._310p.ops.mm_encoder_attention import AscendMMEncoderAttention310
@@ -637,6 +638,8 @@ def register_ascend_customop(vllm_config: VllmConfig | None = None):
                 "RotaryEmbedding": AscendRotaryEmbedding310,
                 "RMSNorm": AscendRMSNorm310,
                 "GemmaRMSNorm": AscendGemmaRMSNorm310,
+                "FusedMoE": AscendFusedMoE310,
+                "SharedFusedMoE": AscendSharedFusedMoE310,
             }
         )