feat(window): template as window title

[katebatura]

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• I read and followed the CONTRIBUTING.md guide.
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Short description of what this resolves:

Closes: #2913

how to use:

Two properties have been added to NbWindowConfig:

• titleTemplate?: TemplateRef<any> use it instead of property title.
• titleTemplateContext?: Object title as template may receive data through this property.

@Component({
  template: `
    <button (click)="openWindow()" nbButton>Open window</button>

    <ng-template #titleTemplate let-data>
      <p>Here is the text provided via config: "{{ data.text }}"</p>
    </ng-template>
  `
})
export class WindowComponent {
  @ViewChild('titleTemplate') titleTemplate: TemplateRef<any>;

  constructor(private windowService: NbWindowService) {}

  openWindow() {
    this.windowService.open(
      SomeComponent,
      {
        titleTemplate: this.titleTemplate,
        titleTemplateContext: {text: 'some text to pass into template'},
      },
    );
  }
}