[Cherry-Pick][Feature] dy-c8 prefix caching

[kevincheng2]

Motivation

dy-c8 support prefix caching
Cherry-Pick from #5125

Modifications

Usage or Command

使用方法(对齐动态c8启动参数 #4475 )：

  python -m fastdeploy.entrypoints.openai.api_server \
       ...
       --enable-prefix-caching \
       --disable-chunked-mm-input \
       --quantization '{"dense_quant_type":"block_wise_fp8", "moe_quant_type":"block_wise_fp8", "quantization":"mix_quant", "kv_cache_quant_type":"block_wise_fp8"}' 

Accuracy Tests

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!