fix: align backend capabilities, tests, and docs

[gongchensu]

Summary

• Register Ascend Graph replay testing and correct its async memset expectations in native and dispatch tests.
• Require aclmdlRIDestroy for Ascend Graph availability and validate that captured Graph handles are non-null.
• Document the Ascend RI runtime requirement and include Cambricon in accelerator backend mutual-exclusion checks.

Motivation

Ascend Graph capture and replay were implemented, but the replay test was not registered for Ascend builds and async memset was still expected to be unsupported.

Graph availability also did not require aclmdlRIDestroy, allowing an incomplete RI lifecycle to be reported as supported. In addition, WITH_CAMBRICON was missing from the accelerator backend mutual-exclusion check.

No linked issue.

Type of Change

• feat - new feature / new backend capability / new public API
• fix - bug fix
• perf - performance improvement without behavior change
• refactor - code restructuring without behavior change
• test - adding or fixing tests only
• docs - documentation only
• build / ci - build system or CI configuration
• chore - tooling, formatting, or other non-code changes
• Breaking change (requires a ! in the Conventional Commits prefix or a BREAKING CHANGE: footer)

Platforms Affected

• CPU (WITH_CPU)
• NVIDIA (WITH_NVIDIA)
• Iluvatar (WITH_ILUVATAR)
• Hygon (WITH_HYGON)
• T-Head (WITH_THEAD)
• MetaX (WITH_METAX)
• Moore (WITH_MOORE)
• Cambricon (WITH_CAMBRICON)
• Ascend (WITH_ASCEND)
• Build system / CMake / generated headers
• Public headers / installed consumer API
• Documentation only

Smoke Build and Test Result

paste smoke build and test output here

Test Results on Supported Platforms

Platform	Affected	Build / Smoke Result	Full Result / Notes
CPU
NVIDIA
Iluvatar
Hygon
MetaX
Moore
Cambricon
Ascend

Full `ctest` output (optional)

paste here

Benchmark / Performance Impact

Notes for Reviewers