[Improve][Connector-V2] Add the nullable attribute of the field for paimon

[hawk9821]

…imon table converts the Column object. #7231

Purpose of this pull request

Does this PR introduce any user-facing change?

How was this patch tested?

Check list

• [ ] If any new Jar binary package adding in your PR, please add License Notice according New License Guide
• [ ] If necessary, please update the documentation to describe the new feature. https://github.com/apache/seatunnel/tree/dev/docs
• [ ] If you are contributing the connector code, please check that the following files are updated:
  1. Update change log that in connector document. For more details you can refer to connector-v2
  2. Update plugin-mapping.properties and add new connector information in it
  3. Update the pom file of seatunnel-dist
• [ ] Update the release-note.

[Hisoka-X]

cc @dailai and @TaoZex as well.

[dailai]

Please change the title of this pr named "[Improve][Connector-V2] Add the nullable attribute of the field for paimon"

@hawk9821 Please read the doc