支持自定义StarRocksGenericRowTransformer 清洗数据

[renzhimin7]

What type of PR is this：

• [ ] Feature

  Which issues of this PR fixes ：

  https://github.com/StarRocks/starrocks-connector-for-apache-flink/issues/323

Problem Summary(Required) ：

Checklist:

• [ ] I have added test cases for my bug fix or my new feature
• [ ] This pr will affect users' behaviors
• [ ] This pr needs user documentation (for new or modified features or behaviors)
• [ ] I have added documentation for my new feature or new function

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