[REQ] [ruby] Reduce code duplication

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

The code generated under Ruby contains a significant amount of duplication. This duplication leads to code bloat both in file size and runtime memory usage.

I propose a base class for models, from which all models would inherit that would contain a lot of this shared logic.

@cliffano @zlx @autopp

Describe the solution you'd like

Initially, I'd like to introduce a new ApiModelBase class from which all base models would inherit. All models that have a parent would continue to inherit from their parent. In the initial PR introducing this new base model, I will move in all model methods that are static and that don't change per child class. This will set up the pattern after which follow up PRs can start moving other common methods and logic down to further eliminate duplication.

Describe alternatives you've considered

N/A

Additional context

I've started a PR to see how feasible it is, and I've created a draft PR in #22052.

I've also executed this against one of my gems and the file size dropped from 16MB to 12MB (25% reduction) even with only the small handful of common methods pulled out. See https://github.com/ManageIQ/kubevirt-sdk-ruby/compare/master...Fryguy:kubevirt-sdk-ruby:reduce_gem_size

Start by reviewing draft PR #22052 and the generated Ruby model output to understand the proposed ApiModelBase pattern and current inheritance structure. Done means introducing the base model, preserving parent-model inheritance, and moving shared static methods into it without changing generated model behavior.