[NPU][Refactor] Rename Diffusion* to Generation*

[gcanlin]

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

Purpose

Follow #163.

Test Plan

python examples/offline_inference/qwen2_5_omni/end2end.py --output-wav output_audio --query-type text

Test Result

[Stage-2] Max batch size: 1
--------------------------------
[Stage-2] Received batch size=1, request_ids=[0]
--------------------------------
(EngineCore_DP0 pid=854566) INFO:vllm_omni.model_executor.models.qwen2_5_omni.qwen2_5_omni:Currently, we do not use the chunked process, we only use the token2wav.process_chunk for the whole sequence. The stream mode will be implemented in the future.
Modular Diffusers is currently an experimental feature under active development. The API is subject to breaking changes in future releases.
INFO 12-05 07:31:43 [__init__.py:36] Available plugins for group vllm.platform_plugins:
INFO 12-05 07:31:43 [__init__.py:38] - ascend -> vllm_ascend:register
INFO 12-05 07:31:43 [__init__.py:41] All plugins in this group will be loaded. Set `VLLM_PLUGINS` to control which plugins to load.
INFO 12-05 07:31:43 [__init__.py:207] Platform plugin ascend is activated
INFO 12-05 07:31:43 [importing.py:63] Triton not installed or not compatible; certain GPU-related functions will not be available.
WARNING 12-05 07:31:44 [_custom_ops.py:20] Failed to import from vllm._C with ModuleNotFoundError("No module named 'vllm._C'")
...[Stage-2] Generate done: batch=1, req_ids=[0], gen_ms=131502.7
('Warning: torch.save with "_use_new_zipfile_serialization = False" is not recommended for npu tensor, which may bring unexpected errors and hopefully set "_use_new_zipfile_serialization = True"', 'if it is necessary to use this, please convert the npu tensor to cpu tensor for saving')
INFO:vllm_omni.entrypoints.omni_llm:[Summary] {'e2e_requests': 1, 'e2e_total_time_ms': 155054.5117855072, 'e2e_sum_time_ms': 155054.1956424713, 'e2e_total_tokens': 0, 'e2e_avg_time_per_request_ms': 155054.1956424713, 'e2e_avg_tokens_per_s': 0.0, 'wall_time_ms': 155054.5117855072, 'final_stage_id': 2, 'stages': [{'stage_id': 0, 'requests': 1, 'tokens': 49, 'total_time_ms': 1526.3910293579102, 'avg_time_per_request_ms': 1526.3910293579102, 'avg_tokens_per_s': 32.101865811287084}, {'stage_id': 1, 'requests': 1, 'tokens': 865, 'total_time_ms': 21992.52414703369, 'avg_time_per_request_ms': 21992.52414703369, 'avg_tokens_per_s': 39.331547130149204}, {'stage_id': 2, 'requests': 1, 'tokens': 0, 'total_time_ms': 131512.49384880066, 'avg_time_per_request_ms': 131512.49384880066, 'avg_tokens_per_s': 0.0}], 'transfers': [{'from_stage': 0, 'to_stage': 1, 'samples': 1, 'total_bytes': 1652666, 'total_time_ms': 2.309560775756836, 'tx_mbps': 5724.607093600908, 'rx_samples': 1, 'rx_total_bytes': 1652666, 'rx_total_time_ms': 4.258155822753906, 'rx_mbps': 3104.9422685169093, 'total_samples': 1, 'total_transfer_time_ms': 7.098674774169922, 'total_mbps': 1862.506512921072}, {'from_stage': 1, 'to_stage': 2, 'samples': 1, 'total_bytes': 2631, 'total_time_ms': 0.35381317138671875, 'tx_mbps': 59.48902330997304, 'rx_samples': 1, 'rx_total_bytes': 2631, 'rx_total_time_ms': 0.05698204040527344, 'rx_mbps': 369.3795422259414, 'total_samples': 1, 'total_transfer_time_ms': 1.2493133544921875, 'total_mbps': 16.847654693129773}]}
Request ID: 0, Text saved to output_audio/00000.txt
Request ID: 0, Saved audio to output_audio/output_0.wav

---

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• 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.
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[hsliuustc0106]

lgtm