GNOME's Glycin breaks within AppImages

I have switched to GTK 4, which includes using Glycin.

This makes my AppImage very angry:

```python
gi.repository.GLib.GError: gdk-pixbuf-error-quark: Failed to load image
“/tmp/.mount_sc-con9BARAK/usr/share/scc/images/controller-icons/unknown.svg”: Could not spawn the following command. Is the used binary available?
`env -i XDG_RUNTIME_DIR="/run/user/1000" "/home/user/Downloads/squashfs-root/usr/libexec/glycin-loaders/2+/glycin-svg" "--dbus-fd" "43"`
: No such file or directory (os error 2) (0)
```

Turns out that at least one issue is Glycin hardcoding paths in its config files:

```yaml
squashfs-root/usr/share/glycin-loaders/2+/conf.d/glycin-svg.conf:Exec=/usr/libexec/glycin-loaders/2+/glycin-svg
squashfs-root/usr/share/glycin-loaders/2+/conf.d/glycin-svg.conf:Exec=/usr/libexec/glycin-loaders/2+/glycin-svg
squashfs-root/usr/share/glycin-loaders/2+/conf.d/glycin-heif.conf:Exec=/usr/libexec/glycin-loaders/2+/glycin-heif
squashfs-root/usr/share/glycin-loaders/2+/conf.d/glycin-heif.conf:Exec=/usr/libexec/glycin-loaders/2+/glycin-heif
squashfs-root/usr/share/glycin-loaders/2+/conf.d/glycin-heif.conf:Exec=/usr/libexec/glycin-loaders/2+/glycin-heif
squashfs-root/usr/share/glycin-loaders/2+/conf.d/glycin-heif.conf:Exec=/usr/libexec/glycin-loaders/2+/glycin-heif
squashfs-root/usr/share/glycin-loaders/2+/conf.d/glycin-jxl.conf:Exec=/usr/libexec/glycin-loaders/2+/glycin-jxl
squashfs-root/usr/share/glycin-loaders/2+/conf.d/glycin-jxl.conf:Exec=/usr/libexec/glycin-loaders/2+/glycin-jxl
squashfs-root/usr/share/glycin-loaders/2+/conf.d/glycin-image-rs.conf:Exec=/usr/libexec/glycin-loaders/2+/glycin-image-rs
squashfs-root/usr/share/glycin-loaders/2+/conf.d/glycin-image-rs.conf:Exec=/usr/libexec/glycin-loaders/2+/glycin-image-rs
```

Though am not sure how to go about fixing that, and appimage-builder should probably be dealing with it automatically in the first place.

Forking https://github.com/C0rn3j/sc-controller/tree/v1.0.0 and running the GitHub Action should be enough to reproduce the failing .AppImage files if needed.

*Downstream report over at https://github.com/C0rn3j/sc-controller/issues/150*