feat(forms): Add FormArrayDirective

[JeanMeche]

The FormArrayDirective will allow to have a FormArray as a top-level form object.

• NgControlStatusGroup directive will be applied to the FormArrayDirective
• NgForm will still create a FormGroup

Usage :

@Component({
  selector: 'form-array-comp',
  template: `
    <form [formArray]="form">
      @for(_ of controls; track $index) {
        <input [formControlName]="$index">
      }
    </form>`,
})
class FormArrayComp {
  controls = [new FormControl('fish'), new FormControl('cat'), new FormControl('dog')];
  form = new FormArray(this.controls);
}

Fixes #30264