[feat] support dispatch_v2/combine_v2 hierarchy communication (#7698)

### What this PR does / why we need it?

This PR adds support for hierarchical communication for `dispatch_v2`
and `combine_v2` MoE operations. This is achieved by introducing a new
configuration `enable_mc2_hierarchy_comm`. When enabled, the
communication algorithm is set to "hierarchy", which support mc2 op comm
between two super pod.

The changes include:
- Adding `enable_mc2_hierarchy_comm` to `AscendConfig`.
- Modifying `TokenDispatcherWithMC2` to pass `comm_alg: "hierarchy"` to
the underlying `torch_npu` ops when the new config is enabled.
- Adding validation to ensure that this feature is only used with
compatible PTA/CANN versions and is not used with the conflicting
`fused_mc2` op.
- Updating `is_hierarchical_communication_enabled` to respect the new
configuration flag.

### Does this PR introduce _any_ user-facing change?

Yes, this PR introduces a new user-facing configuration option
`enable_mc2_hierarchy_comm` in `additional_config` to enable
hierarchical communication for MoE.

### How was this patch tested?

- vLLM version: v0.18.0

Signed-off-by: zzzzwwjj <1183291235@qq.com>

vllm_ascend/ascend_config.py

@@ -165,6 +165,9 @@ class AscendConfig:
             and vllm_config.compilation_config.pass_config.enable_sp
         )
 
+        # Enable dispatch/combine op inter-node communication by ROCE
+        self.enable_mc2_hierarchy_comm = additional_config.get("enable_mc2_hierarchy_comm", False)
+
     @staticmethod
     def _get_compile_ranges(compilation_config):
         return compilation_config.compile_ranges_endpoints or []