### What this PR does / why we need it?
Add installation script of `fused_infer_attention_score` kernel with
flash decoding
### Userface changes
Users can install the kernel `fused_infer_attention_score` with flash
decoding feature by `bash
tools/install_flash_infer_attention_score_ops_a2.sh` or `bash
tools/install_flash_infer_attention_score_ops_a3.sh`
- vLLM version: release/v0.13.0
- vLLM main:
254f6b9867
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Signed-off-by: MengqingCao <cmq0113@163.com>