Remove notebooks UI (#1779)

* Fix API endpoint for CassandraProxy query API

* Remove notebooks UI components

* Fix tests

* Address comments

* Fix unit tests

* Remove commented code

src/Explorer/Tree/ResourceTreeAdapter.tsx

@@ -800,11 +800,6 @@ export class ResourceTreeAdapter implements ReactAdapter {
         iconSrc: NewNotebookIcon,
         onClick: () => this.container.onCreateDirectory(item),
       },
-      {
-        label: "New Notebook",
-        iconSrc: NewNotebookIcon,
-        onClick: () => this.container.onNewNotebookClicked(item),
-      },
       {
         label: "Upload File",
         iconSrc: NewNotebookIcon,