Add fabrikt generator github action

[thejeff77]

This is a feature request to build a github action. Similar to the Openapi tools one.

I am happy to build this or have anyone else do it .. as I've built an internal one already, but I figured I'd open an issue to discuss first. Here are some things I think warrant discussion:

• It needs its own repository, where will it live?
• Would we use a config file similar to what openapi tools has? How will this file look and how will it translate into command line args?

[cjbooms]

This would be a really nice contribution.

I'm happy to support in any way I can. It's not something I'm familiar with and there are no other similar plans in the works so it's really up to you to drive as you like. Thoughts:

1. I've no preference on location. I can open another repo and give you access, or we can link out to a new repo you create in the Readme. Whatever you think works best.

2. Intuitively, I'd say keep the config as close to the main method CLI parameters as possible. We could define an OpenApi3 schema for them if that helps.