Grids: Custom validator samples don't compile

[ddaribo]

Open these samples in StackBlitz:

1. https://www.infragistics.com/products/ignite-ui-angular/angular/components/grid/validation#example
2. https://www.infragistics.com/products/ignite-ui-angular/angular/components/treegrid/validation#example
3. https://www.infragistics.com/products/ignite-ui-angular/angular/components/hierarchicalgrid/validation#example

All fail to compile due to the custom validator declaration:

Class 'PhoneFormatDirective' used before its declaration.(2449)
grid-validator-service-extended.component.ts(21, 14): 'PhoneFormatDirective' is declared here.
class PhoneFormatDirective

Applying forwardRef would fix these, i.e.:

providers: [
  {
    provide: NG_VALIDATORS,
    useExisting: forwardRef(() => PhoneFormatDirective),
    multi: true
  }
]