feat: convert NavItem to class

npm/ng-packs/packages/theme-shared/src/lib/models/nav-item.ts

@@ -1,6 +1,6 @@
 import { Type } from '@angular/core';
 
-export interface NavItem {
+export class NavItem {
   id: string | number;
   component?: Type<any>;
   html?: string;
@@ -8,4 +8,8 @@ export interface NavItem {
   order?: number;
   requiredPolicy?: string;
   visible?: () => boolean;
+  constructor(props: Partial<NavItem>) {
+    props = { ...props, visible: props.visible || (() => true) };
+    Object.assign(this, props);
+  }
 }