migrate notebook_viewer to dynamic import

app/assets/javascripts/blob/notebook_viewer.js

 import renderNotebook from './notebook';
 
-document.addEventListener('DOMContentLoaded', renderNotebook);
+export default renderNotebook;

app/assets/javascripts/blob/viewer/index.js

@@ -32,6 +32,9 @@ export default class BlobViewer {
       case 'balsamiq':
         initViewer(import(/* webpackChunkName: 'balsamiq_viewer' */ '../balsamiq_viewer'));
         break;
+      case 'notebook':
+        initViewer(import(/* webpackChunkName: 'notebook_viewer' */ '../notebook_viewer'));
+        break;
       default:
         break;
     }

app/views/projects/blob/viewers/_notebook.html.haml

-- content_for :page_specific_javascripts do
-  = webpack_bundle_tag('common_vue')
-  = webpack_bundle_tag('notebook_viewer')
-
 .file-content#js-notebook-viewer{ data: { endpoint: blob_raw_path } }

config/webpack.config.js

@@ -50,7 +50,6 @@ function generateEntries() {
   const manualEntries = {
     monitoring:           './monitoring/monitoring_bundle.js',
     mr_notes:             './mr_notes/index.js',
-    notebook_viewer:      './blob/notebook_viewer.js',
     pdf_viewer:           './blob/pdf_viewer.js',
     protected_branches:   './protected_branches',
     registry_list:        './registry/index.js',
@@ -249,7 +248,6 @@ const config = {
         'groups',
         'monitoring',
         'mr_notes',
-        'notebook_viewer',
         'pdf_viewer',
         'pipelines',
         'pipelines_details',