fix: fix mysql-cdc case sensitive

[a120610114]

修复 mysql-cdc 因为大小写敏感导致 非自增型主键 chunks 分配大小不均匀问题。

修复逻辑： 1、mysqlcdc 非自增型主键方法均会走splitUnevenlySizedChunks 方法。 2、在splitUnevenlySizedChunks方法中在chunks之前判断主键collation 是否大小写敏感 3、mysql中字段类型 collation 为null 以及是以_ci 结尾的都是大小写不敏感的 4、如果主键大小写敏感，则走原逻辑。如果主键大小写不敏感则统一将字符转换为小写字符串 再进行ObjectUtils.compare比较

[leonardBang]

@a120610114 The changes looks well, could you add a test to validate the change?

[yuxiqian]

Hello @shizhengchao, sorry for the long delay of this PR. Could you please help rebase it with latest master branch before we can merge this?

Kindly reminder about some refactored packages:

• MySQLTableSource and MySQLTableSourceFactory com.ververica.cdc.connectors.mysql.table → org.apache.flink.cdc.connectors.mysql.table

Thanks again for your generous contribution!

[github-actions[bot]]

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