Remove NotebookViewerTab (#749)

[Preview this branch](https://cosmos-explorer-preview.azurewebsites.net/pull/749)

src/Explorer/Explorer.tsx

@@ -1,6 +1,5 @@
-import * as ko from "knockout";
 import { IChoiceGroupProps } from "@fluentui/react";
-import * as path from "path";
+import * as ko from "knockout";
 import Q from "q";
 import React from "react";
 import _ from "underscore";
@@ -1843,39 +1842,6 @@ export default class Explorer {
     }
   }
 
-  public async openNotebookViewer(notebookUrl: string) {
-    const title = path.basename(notebookUrl);
-    const hashLocation = notebookUrl;
-    const NotebookViewerTab = await (
-      await import(/* webpackChunkName: "NotebookViewerTab" */ "./Tabs/NotebookViewerTab")
-    ).default;
-
-    const notebookViewerTab = this.tabsManager.getTabs(ViewModels.CollectionTabKind.NotebookV2).find((tab) => {
-      return tab.hashLocation() == hashLocation && tab instanceof NotebookViewerTab && tab.notebookUrl === notebookUrl;
-    });
-
-    if (notebookViewerTab) {
-      this.tabsManager.activateNewTab(notebookViewerTab);
-    } else {
-      const notebookViewerTab = new NotebookViewerTab({
-        account: userContext.databaseAccount,
-        tabKind: ViewModels.CollectionTabKind.NotebookViewer,
-        node: null,
-        title: title,
-        tabPath: title,
-        collection: null,
-        hashLocation: hashLocation,
-        isTabsContentExpanded: ko.observable(true),
-        onLoadStartKey: null,
-        onUpdateTabsButtons: this.onUpdateTabsButtons,
-        container: this,
-        notebookUrl,
-      });
-
-      this.tabsManager.activateNewTab(notebookViewerTab);
-    }
-  }
-
   public onNewCollectionClicked(databaseId?: string): void {
     if (userContext.apiType === "Cassandra") {
       this.cassandraAddCollectionPane.open();