feature request: enum values not supported in json schema

[cdaringe]

problem

when auto-generating my schema, i have to programmatically walk my definition tree and remove any enum usages due to https://github.com/electrode-io/electrode-native/issues/1449

#1449 is about a failure being swallowed and proceeding, but this ticket is about formally supporting the specific data type demonstrating the failure mode

[LcTwisk]

@friederbluemle @belemaire I've added enum codegen locally, it's not perfect but already quite nice. I'd like to share what I got with you guys, and start a discussion about the requirements. Would that be possible? If so, what would be a nice way to do it? I can open a PR with my current progress and add some discussion points/comments to it.