Remove usage of Electron context menus

Summary: Removed the usage of electron's native context menus, and replaces it with Antd based context menu's.

Reviewed By: passy

Differential Revision: D31990756

fbshipit-source-id: 0312cbac5fd20a1a30603ce1058c03f4291b23b1

desktop/plugins/public/network/request-mocking/NetworkRouteManager.tsx

@@ -8,8 +8,6 @@
  */
 
 import fs from 'fs';
-// eslint-disable-next-line
-import electron, {OpenDialogOptions, remote} from 'electron';
 import {Atom, DataTableManager, getFlipperLib} from 'flipper-plugin';
 import {createContext} from 'react';
 import {Header, Request} from '../types';