- move all icons to the icons directory
- rename some icons to be more meaningful
- put all icons on a resource sheet
- update references to icon name changes
- deprecate icons for those in standard set
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2141>
Now that the extension preference dialog is opened by a separate
D-Bus service rather than the Extensions app, it can be opened
without a parent window that provides name and icon.
Fix this by adding back a hidden .desktop file.
https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/2562