[Improve][Connector-V2][File] Improve code structure

[TyrantLucifer]

Purpose of this pull request

Improve code structure, make code more clearly.

Check list

• [x] Code changed are covered with tests, or it does not need tests for reason:
• [ ] 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/incubator-seatunnel/tree/dev/docs

[EricJoy2048]

Please fix CI error.