Add support for ads in browser console output

Proof of concept for text display from a separate json file,
all array items of key 'hi' are printed to the browser console.

packages/app-shell/src/app-shell.js

@@ -261,8 +261,16 @@ export class AppShell extends ScopedElementsMixin(DBPLitElement) {
         if (this.src)
             this.fetchMetadata(this.src);
         this.initRouter();
+
+        this.showAdvertisment();
     }
 
+    async showAdvertisment() {
+        const url = this.basePath + 'exit-vim.json';
+        await fetch(url, { headers: {'Content-Type': 'application/json'} })
+            .then(response => response.json())
+            .then(data => data['hi'].forEach(item => console.log(item)));
+    }
     /**
      * Switches language if another language is requested
      *

toolkit-showcase/assets/exit-vim.json

+{
+  "hi" : [
+    "********************************************",
+    "* Hi, curious developer!                   *",
+    "* Join us at Graz University of Technology *",
+    "* See https://tugraz.at/open-positions?    *",
+    "********************************************"
+    ]
+}
\ No newline at end of file

toolkit-showcase/rollup.config.js

@@ -160,6 +160,7 @@ Dependencies:
                 {src: 'assets/icon-*.png', dest: 'dist/' + await getDistPath(pkg.name)},
                 {src: 'assets/manifest.json', dest: 'dist', rename: pkg.name + '.manifest.json'},
                 {src: 'assets/silent-check-sso.html', dest:'dist'},
+                {src: 'assets/exit-vim.json', dest:'dist'},
                 {src: await getPackagePath('@dbp-toolkit/font-source-sans-pro', 'files/*'), dest: 'dist/' + await getDistPath(pkg.name, 'fonts/source-sans-pro')},
                 {src: await getPackagePath('@dbp-toolkit/common', 'src/spinner.js'), dest: 'dist/' + await getDistPath(pkg.name)},
                 {src: await getPackagePath('@dbp-toolkit/common', 'misc/browser-check.js'), dest: 'dist/' + await getDistPath(pkg.name)},