feat: Add bitmap java demo

[taoshengyijiua]

Add relevant examples of bitmap java to help you operate bitmap in java, or you can convert the original data into bitmap, then serialize it into base64 string, and then import it into the bitmap type fields corresponding to the StarRocks table, which can greatly reduce data transmission Signed-off-by: tao.zhou tao.zhou@ly.com

[CLAassistant]

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