fix: add antergos-wallpapers to rootfs packages, restore Install Artix hide

- antergos-wallpapers now installed into rootfs so the KDE wallpaper picker
  shows the Antergos wallpaper automatically (package installs to
  /usr/share/wallpapers/antergos-wallpaper/ with metadata.desktop).
- Restored calamares-config-switcher.desktop in live-overlay with
  NoDisplay=true to hide 'Install Artix' from the app menu. Previous deletion
  exposed the package version, making it visible again.

iso-profiles/antergos/live-overlay/usr/share/applications/calamares-config-switcher.desktop

@@ -0,0 +1,14 @@
+[Desktop Entry]
+Type=Application
+Version=1.0
+Name=Install Artix
+GenericName=System Installer
+Keywords=calamares;system;installer;
+TryExec=calamares-config-switcher
+Exec=calamares-config-switcher
+Comment=Calamares — System Installer
+Icon=artixlinux-logo
+Terminal=false
+StartupNotify=true
+Categories=Qt;System;
+NoDisplay=true