Add support to validate nested objects

[villander]

We'd like to have the ability to copy the model and apply validations without creating N @tracked properties to every model field we want to validate into the component.

import Model, { attr } from '@ember-data/model';

export default class MyModel extends Model {
  @attr('string') details;
  @attr('string') name;
  @attr('string') color;
}

import Component from '@ember/component';
import { objectValidator } from 'ember-model-validator';

@objectValidator
export default class MyComponent extends Component {
  @tracked formData;

  constructor(
    owner: unknown,
    args: CompSignature['Args'],
  ) {
    super(owner, args);

    this.formData = this.args.model;
  }
  
 validations = {
    formData: { 
      details: { presence: true },
    }
 };
  
}