[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/ascend_forward_context.py

@@ -208,6 +208,7 @@ def select_moe_comm_method(num_tokens: int, vllm_config: VllmConfig, is_draft_mo
     4. On A3 with expert parallel, prefer fused MC2 when using w8a8_dynamic
        quantization with small EP size, no dynamic_eplb, and not in MTP
        mode; otherwise use MC2 within capacity or all-to-all.
+    5. On 310P, always use all-gather.
 
     Args:
         num_tokens (int): The number of tokens in the current batch.
@@ -262,7 +263,8 @@ def select_moe_comm_method(num_tokens: int, vllm_config: VllmConfig, is_draft_mo
             elif envs_ascend.VLLM_ASCEND_ENABLE_FUSED_MC2 == 2:
                 fused_prefill_enable = False
             moe_comm_type = MoECommType.FUSED_MC2 if fused_prefill_enable else MoECommType.ALLTOALL
-
+    elif soc_version in {AscendDeviceType._310P}:
+        moe_comm_type = MoECommType.ALLGATHER
     else:
         raise ValueError(f"Unsupported soc_version: {soc_version}")
     return moe_comm_type