[Feature][Connectors-V2][File]support assign encoding for file source/sink

[ShaunWuu]

Purpose of this pull request

This pull request support assign encoding for file source/sink

Does this PR introduce any user-facing change?

Yes.
A config to assign encoding for file source/sink. The name of the config is "encoding".
This pr is within the unreleased branch dev.

One of the example:

LocalFile {
    path = "/tmp/hive/warehouse/test2"
    file_format_type = "text"
    encoding = "gbk"
}

How was this patch tested?

Unit tests are as the followings:

• org.apache.seatunnel.connectors.seatunnel.file.writer.ReadStrategyEncodingTest

E2E test cases are as the followings:

• org.apache.seatunnel.e2e.connector.file.local.LocalFileIT

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.

[hailin0]

cc @TyrantLucifer

[ShaunWuu]

force-pushed the dev-240304-fileEncoding branch from d5adc8c to 424ca42

This force push deleted a redundant line of code.

[lightzhao]

#5973 cc @EricJoy2048

[Hisoka-X]

Overall LGTM