Adds a feature which randomizes the wallpaper based on a user defined interval by creating a script for the user

[chrissolanilla]

Hello, this is my fork of Waypaper. I have implemented a new feature that enhances user customization by allowing the wallpaper to be randomized at user-defined intervals. This feature includes the following:

• New Button: A button has been added to the main interface which, when clicked, opens a menu.
  

• Interval Setting: The menu provides an option for users to input an interval in seconds, specifying how frequently the wallpaper should change.
  

• Start/Stop Script: The menu also includes options to start or stop the script responsible for changing the wallpaper at the defined interval.
  

• Script Execution: When the interval is set, a script is created and executed to handle the wallpaper changes at the specified frequency. The user can stop this script anytime using the menu.
  

This is my first time potentially contributing to an open-source project, so it would mean a lot if you could accept my pull request. I am happy to do any revisions or changes as needed. Thank you for considering my contribution.