[NPU] add A5/ascend950 support for A2E and E2A ops

[wangyibo1005]

Register ascend950, gate SetCommEngine as HcclAccelerator::AIV on the 950 host build, and use the A5 MTE window layout (1MB state region, 1KB per-rank step) while 910C stays on the existing remoteRes path.

PLEASE FILL IN THE PR DESCRIPTION AND MAKE SURE THE CHECKLIST ITEMS HAVE BEEN CONSIDERED.

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• Closing keyword, only if fully resolved: Closes #

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Essential PR Checklist

• Purpose is clear and linked to public context when possible.
• Scope is bounded.
• Compatibility with vLLM v0.26.0 is considered.
• No changes are made to the vLLM source checkout.
• Plugin-owned classes or explicit dotted class paths are preferred over monkey patches.
• Any compat shim or monkey patch is isolated, idempotent, version-guarded, documented, and tested.
• Imports remain CPU-safe; CUDA-heavy work is delayed or GPU-gated.
• Validation evidence is included, including skipped GPU tests when applicable.
• Documentation impact is stated.

[jiangkuaixue123]

Does the existing A3 functionality still work correctly with these changes?

[wangyibo1005]

Does the existing A3 functionality still work correctly with these changes?

Operators build respectively by indicating different SOC_VERSION, this pull request never changes any code of A3