[WIP] Add Ascend NPU Backend Support for Qwen2.5-Omni

[AndyZhou952]

PLEASE FILL IN THE PR DESCRIPTION HERE ENSURING ALL CHECKLIST ITEMS (AT THE BOTTOM) HAVE BEEN CONSIDERED.

Purpose

Draft implementation of #67.

Test Plan

TBD

Test Result

TBD

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft.

BEFORE SUBMITTING, PLEASE READ https://github.com/vllm-project/vllm-omni/blob/main/CONTRIBUTING.md (anything written below this line will be removed by GitHub Actions)

[hsliuustc0106]

the worker, model_runner classes should be moved to the vllm-ascend project later. Currently, we can work out it here to test the functionality

[AndyZhou952]

Rebased onto #76 and opened as a new PR #89. Closing this one.