Lazy load model properties

Demonstration API definition

petstore.swagger.io/...&url=https://heldersepu.github.io/hs-scripts/swagger/4248_swagger.json

Expected Behavior

Fast expansion of model properties

Current Behavior

Very slow expansion of model properties

Possible Solution

Lazy load model properties like we do the models

Context

Looking at the current implementation, the collapsed models show right away (big thanks 2 @shockey)

Expanding small models is quick, but the largest models (such as Patrimonio ) takes quite a while, once it fully expands, expanding child models takes no time...
I believe that is because we are loading the entire tree of the model.

Reproduce the delay with the linked PetStore demonstration API, especially the large Patrimonio model, and inspect the existing model and property expansion flow. The change is done when model properties expand without eagerly loading the entire child tree and the observed expansion delay is substantially reduced; the issue names no files or tests to start from.