[Feature] [core][general] Opportunity to configure metadata file names

Created by: poisonedvk

Description

In our project we have multiple repositories with specifications which are connected to it. When generator generates classes for all of connected specifications, it overwrites metadata files which called FILES and VERSION. The problem is that we have no opportunity to configure names of metadata files. They are constants in DefaultGenerator class: "FILES" and "VERSION". If we have this opportunity, we could name files in a specific way and metadata files would not be overwritten.

openapi-generator version

5.1.1

Suggest a fix/enhancement

I'm gonna make a pull request with above mentioned parameters configured inside DefaultCodegen class and used inside DefaultGenerator.