Support for NativeScript v9 sectioned ListView with Angular templates

Is your feature request related to a problem? Please describe.
NativeScript 9 introduced native sectioned ListView support with sticky headers (Announcement). This feature is not yet supported with @nativescript/angular templates.

Describe the solution you'd like
Support for Angular templates in sectioned ListView:

<ListView sectioned="true" stickyHeader="true" [items]="sections">
  <ng-template nsTemplateKey="header" let-section>
    <Label [text]="section.title"></Label>
  </ng-template>
  <ng-template nsTemplateKey="item" let-item>
    <Label [text]="item.name"></Label>
  </ng-template>
</ListView>

Describe alternatives you've considered
Flattening sections into a single array with type discriminator and using itemTemplateSelector, but this loses native sticky header behavior.

Additional context

• @nativescript/core: 9.x
• @nativescript/angular: 20.0.0, 21.0.0-rc0
• iOS / Android

Comienza en la integración de plantillas de ListView de @nativescript/angular y compara cómo se gestionan los valores de nsTemplateKey para las plantillas de elementos. Verifica el ejemplo de sectioned y sticky-header con NativeScript core 9.x en iOS y Android; se considera terminado cuando ambas plantillas de Angular se renderizan con encabezados de sección nativos y comportamiento de sticky-header.