System to create Models

[Androlax2]

Add a system to create Models directly from an API for example :

export class TypedFoo extends ContentItem<FooModel> {
  static modelName = 'foo';
  
  definition(): FooModel {
    return {
      title: 'Typed Foo Content',
      content: 'This is type-safe!',
      featured: true
    };
  }
}

We could generate typescript interface for FooModel from the DatoCMS and so it'll be typesafe to use and generate models programmatically.
Would be nice to include faker to be able to randomize text, images