fixes [Some of the menu examples don't contain `SafeArea`](https://github.com/flutter/flutter/issues/132388)

### Description

This fixes the menu examples for running on mobile with a safe area.

![Group 2](https://github.com/flutter/flutter/assets/48603081/0d460c00-60f5-45e0-87ee-c010ede9ee42)

Rename Sample classes