Auto Changing Wallpaper

### Problem

No auto changing wallpaper option available.

### Proposal

As an avid user of Elementary OS, I'm constantly impressed by its sleek design and user-friendly interface. However, I believe there's an opportunity to elevate the desktop customization experience in the upcoming Elementary OS 8 release.

My suggestion is to introduce a dynamic wallpaper rotation feature within the System Settings. This feature would allow users to automatically switch wallpapers at varying intervals, providing a refreshing and dynamic visual experience. Users could select a collection of wallpapers from their local storage or curated online sources and set the rotation interval based on their preferences, whether it's every hour, day, or week.

Additionally, I propose expanding customization options for the lock screen background. While the option to use a solid background color or a blur of the current wallpaper is appreciated, many users desire the ability to set a specific wallpaper for the lock screen background. This feature would not only enhance personalization but also maintain visual consistency across the desktop environment.

By integrating these features into System Settings, Elementary OS 8 would empower users to personalize their desktop environments to a greater extent, fostering a deeper sense of ownership and enjoyment of the operating system. I believe these enhancements align with Elementary OS's commitment to providing a polished and user-centric computing experience, and I look forward to seeing them implemented in the upcoming release.

### Prior Art (Optional)

_No response_