Inconsistent Wayland app-id vs X11 WM_CLASS

Summary

Hi there - I noticed that Fluxer will produce different vales for a Wayland app-id vs X11 WM_CLASS. .desktop files will use this ID to determine which app icon to show in taskbars. Since it's not consistent between platforms it's not possible to write a .desktop file that's compatible. Under X11 the WM_CLASS is Fluxer, but under Wayland it's fluxer_app

Steps to reproduce

1. Run Fluxer under a Wayland window manager (in my case - KWIN)
2. Probe for window properties (KDE System Settings -> Window Management -> Window Rules -> Add new ->Click "Detect Window Properties").
3. Observe the class name is "fluxer_app"
4. Run Fluxer under an X11 window manager (in my case - still KWIN, just a different session)
5. Probe for window properties (KDE System Settings -> Window Management -> Window Rules -> Add new ->Click "Detect Window Properties").
6. Observe the class name is "Fluxer"

Environment (optional)

Tested with both stable and canary, attached screenshots are from stable.

Logs or screenshots (optional)

Window Properties - Wayland image Window Properties - X11 image