fix(bottom-navigation): missing angular registerElement

Author: farfromrefug

src/bottom-navigation/angular/index.ts

@@ -1,6 +1,6 @@
 import { Directive, NgModule } from '@angular/core';
 import { registerElement } from '@nativescript/angular';
-import { BottomNavigation } from '@nativescript-community/ui-material-bottom-navigation';
+import { BottomNavigation, TabContentItem, TabStrip, TabStripItem } from '@nativescript-community/ui-material-bottom-navigation';
 
 @Directive({ selector: 'MDBottomNavigation' })
 export class MaterialBottomNavigationDirective {}
@@ -12,3 +12,6 @@ export class MaterialBottomNavigationDirective {}
 export class NativeScriptMaterialBottomNavigationModule {}
 
 registerElement('MDBottomNavigation', () => BottomNavigation);
+registerElement('MDTabStrip', () => TabStrip);
+registerElement('MDTabStripItem', () => TabStripItem);
+registerElement('MDTabContentItem', () => TabContentItem);