[REQ] Openapi generator maven plugin does not support "Supporting files" configuration

Is your feature request related to a problem? Please describe.

I'm trying to use openapi-generator maven plugin to generate JAVA SDK based on the OAS yaml file. Apart from the API and models, I'd like to generator a utility java file with the template engine. I went through the official document that said it can be achieved by openapi-generator cli with a configuration file(https://openapi-generator.tech/docs/customization/).

templateDir: my_custom_templates
additionalProperties:
  artifactId: kotlin-petstore-client
  serializableModel: "true"
  dateLibrary: java8
files:
  AUTHORS.md: {}
  api_interfaces.mustache:
    templateType: API
    destinationFilename: Interface.kt
  api.mustache:
    templateType: API
    destinationFilename: Impl.kt
  other/check.mustache:
    folder: scripts
    destinationFilename: check.sh
    templateType: SupportingFiles

The check.mustache in the example is actually what I need(define a template and convert it to util file), and looks it's simple enough by adding things under the files node. However, I found the openapi-generator maven plugin does not support such files configuration in the pom.xml.

Describe the solution you'd like

Do some configuration in the maven pom to declare the supporting files, just like the CLI approach.

Describe alternatives you've considered

N/A

Additional context

N/A

Start with the openapi-generator Maven plugin configuration in pom.xml and compare it with the CLI customization documentation and its files configuration. Done means Maven users can declare supporting files, templates, destinations, folders, and template types in the pom with behavior equivalent to the CLI.