[core] Allow using lists as globalProperty in config files

[kuhnroyal]

This allows for config files of this sort:

globalProperties:
  skipFormModel: true
  apiTests: false
  modelTests: false
  supportingFiles: ''
  models:
    - Pet
    - Dog
    - User
  apis:
    - UserApi

This is much easier to use than comma separated strings, especially for large lists (I have 50+ models out of 100+)

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[kuhnroyal]

@wing328 @GORA-SAG Do you guys think this is useful? I am using this for a while now in my projects with lots of classes and it really makes it a lot easier to configure.

[GORA-SAG]

@kuhnroyal this is really cool and easy to configure and helpful in cases which involves more classes. typically in that situation providing it in a config file is more easy as we can't provide everything in command line, but for automation kind of stuff which involves some dynamic model changes then the fix that i have done will be helpful. ultimately it's depends on the use case.

[wing328]

@kuhnroyal looks good 👍

To be clear, it's the config file supplied via -c (not a separate config file), right?

[kuhnroyal]

@wing328 Yes, the existing config file that gets passed to the CLI with -c. Where should this be documented?

[wing328]

cc @OpenAPITools/generator-core-team

[wing328]

@kuhnroyal let's go with what you suggest in this PR 👍