Install iproute2 if not already installed.

This package installs the `ip` command used by Ansible to set up Re6st.
It is usually installed by default, but not in the official SLE 15 SP6
Docker image.

See merge request nexedi/slapos.core!655

master/bt5/slapos_web_deploy/PathTemplateItem/web_page_module/deploy_base_setup.txt

@@ -56,6 +56,7 @@ fi
 
 is_package_installed unzip || install_package unzip
 is_package_installed openssl || install_package openssl
+is_package_installed iproute2 || install_package iproute2
 
 if ! is_suse && ! is_ubuntu || [[ $DISTRO = wheezy || $DISTRO == jessie || $DISTRO == stretch || $DISTRO == xenial || $DISTRO == bionic ]]; then
   is_package_installed python-pip || install_package python-pip