[ACA-1970] extension fixes (#780)

* cleanup extension settings

* remove header demo and update schema

* move card view to separate demo extension

* update to ADF 2.6.1

src/app/extensions.module.ts

@@ -1,10 +1,9 @@
 import { NgModule } from '@angular/core';
-import { AcaDevToolsModule } from '@denysvuika/aca-dev-tools';
 
 // Main entry point for external extensions only.
 // For any application-specific code use CoreExtensionsModule instead.
 
 @NgModule({
-  imports: [AcaDevToolsModule]
+  imports: []
 })
 export class AppExtensionsModule {}