Add Placeholder for MenuItem Index Page

[shuningliu]

• [ ] There is a file called 'MenuItemsIndexPage.js' in the 'src/main/pages/MenuItems' directory.
• [ ] The file exports a component with a basic layout, a title 'MenuItems', and placeholder text.
• [ ] In 'App.js', there is a route linking the path '/menuItems/list' to 'MenuItemsIndexPage'