[Feature] Support cute cpp Encoder FA4

[mpgemm]

Motivation

新增优化后的 C++ FA4 算子，支持 NVIDIA SM100 硬件，并将其集成至 FLASH_MASK_ATTN 后端。

Modifications

1. 新增 blackwell_ops 包依赖。（未上传，支持 Encoder，Decoder FA4）
2. 新增 flash_attn_v4 算子 （Encoder FA4)。
3. 将 flash_attn_v4 算子集成到 flash_mask_attn_backend 中。

Usage or Command

# 安装依赖（需要添加三方包 blackwell_ops，目前暂未上传）
python -m pip install -r requirements.txt 

# 安装 FastDeploy
bash build.sh 1 python false [100]

# 启动服务
export FD_ATTENTION_BACKEND=FLASH_MASK_ATTN

python -m fastdeploy.entrypoints.openai.api_server \
      --model $MODEL_PATH \
      --max-model-len 131072 \
      --max-num-seqs 128 \
      --gpu-memory-utilization 0.9 \
      --tensor-parallel-size 1 \
      --port 8112 \
      --engine-worker-queue-port 8113 \
      --metrics-port 8114 \
      --cache-queue-port 8115 \
      --scheduler-port 8117

Accuracy Tests

在[tests/operators/test_flash_mask_attn.py] 中加入正确性验证

Checklist

• Add at least a tag in the PR title.
  • Tag list: [[FDConfig],[APIServer],[Engine], [Scheduler], [PD Disaggregation], [Executor], [Graph Optimization], [Speculative Decoding], [RL], [Models], [Quantization], [Loader], [OP], [KVCache], [DataProcessor], [BugFix], [Docs], [CI], [Optimization], [Feature], [Benchmark], [Others], [XPU], [HPU], [GCU], [DCU], [Iluvatar], [Metax]]
  • You can add new tags based on the PR content, but the semantics must be clear.
• Format your code, run pre-commit before commit.
• Add unit tests. Please write the reason in this PR if no unit tests.
• Provide accuracy results.
• If the current PR is submitting to the release branch, make sure the PR has been submitted to the develop branch, then cherry-pick it to the release branch with the [Cherry-Pick] PR tag.

[paddle-bot]

Thanks for your contribution!

[CLAassistant]

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 53.84615% with 6 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (develop@482f951). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
...ecutor/layers/attention/flash_mask_attn_backend.py	40.00%	3 Missing ⚠️
...del_executor/layers/attention/ops/flash_attn_v4.py	57.14%	3 Missing ⚠️

Additional details and impacted files

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  Coverage           ?   73.92%           
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  Files              ?      400           
  Lines              ?    56413           
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  Hits               ?    41706           
  Misses             ?    11728           
  Partials           ?     2979           

Flag	Coverage Δ
GPU	73.92% <53.84%> (?)

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[RichardWooSJTU]

LGTM