New Shortcuts Editing Dialog

The current GIMP Shortcut Dialog is outdated and not so user-friendly. During this GSoC term (2026), I can contribute improving the Shortcut Dialog. I have planned to implement these five major changes in the shortcut editor. 1. Support for importing and exporting shortcut profiles 2. Replacement of the deprecated GtkTreeView with side-by-side categorized lists to improve navigation. 3. Active keybinding search to quickly locate actions by assigned shortcuts. 4. Ability to assign and manage multiple shortcuts per action. 5. Add the missing icons