KvCacheExtParam(暂未使能)

调用PullKvCache/PullKvBlock时的扩展参数，暂未使能

struct KvCacheExtParam {
  std::pair<int32_t, int32_t> src_layer_range = {-1, -1};
  std::pair<int32_t, int32_t> dst_layer_range{-1, -1};
  uint8_t reserved[128];
};