函数 write_long 

pub(crate) fn write_long<W: Write + ?Sized>(
    out: &mut W,
    value: i64,
) -> Result<(), ArrowError>

使用 ZigZag + 变长编码，将单个 Avro-long 缓冲写入。

规范：https://avro.apache.org/docs/1.11.1/specification/#binary-encoding