[Core/Bugfix] Add query dtype as per FlashInfer API requirements.

[elfiegg]

As per FlashInfer doc, q_data_type will be set to KV cache's data_type if not explicitly set, which results in RuntimeError: BatchPrefillWithPagedKVCachePyTorchWrapper::BeginForward(at::Tensor, at::Tensor, at::Tensor, at::Tensor, unsigned int, unsigned int, unsigned int, unsigned int, unsigned int, at::Tensor)::<lambda()> failed to dispatch data type Float8_e4m3fn.

cc @pavanimajety @yzh119

[github-actions]

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[comaniac]

Thanks for the fix!
Also cc @yzh119