Add "everything" variant for the installer image

It's easy to do but the resulting image is not so useful so we will
likely not generate it.

kali-config/installer-everything/packages

@@ -0,0 +1,19 @@
+# Installer image with kali-linux-everything
+
+# But that image is not really useful, see
+# https://gitlab.com/kalilinux/internal/roadmap/-/issues/363#note_649803259
+
+# Metapackages
+# You can customize the set of Kali metapackages (groups of tools) available
+# in the installer ISO.
+# For the complete list see: https://tools.kali.org/kali-metapackages
+kali-linux-core
+kali-tools-top10
+kali-linux-default
+kali-linux-large
+kali-linux-everything
+
+# Graphical desktops
+kali-desktop-xfce
+kali-desktop-gnome
+kali-desktop-kde