update lib/utils.sh

- add 'is_pkg_a_dependency', to ensure a package is not needed by some others before removing it
-> will be used in debian 12 CIS by at least the 2.1.5 recommendation

- update 'is_service_enabled' to use 'systemd' instead of 'rc.d', as we are now only supporting debian LTS using systemd
- add 'is_using_sbin_init' to ensure we can use systemctl, in case of running on non detected container
- add 'manage_service' to enable / disable service using systemctl

lib/utils.sh

@@ -599,11 +599,12 @@ is_pkg_a_dependency() {
     local known_deps="$*"
 
     PKG_DEPENDENCIES=""
+
     # shellcheck disable=2162
     while read pkg_dep_name; do
         is_pkg_installed "$pkg_dep_name"
         if [ "$FNRET" -eq 0 ] && ! grep -w "$pkg_dep_name" <<<"$known_deps" >/dev/null; then
-            # need a 'if' even for a single sentence, due to 'set -u'
+            # need a 'if' even for a single sentence, due to 'set -e'
             PKG_DEPENDENCIES="$PKG_DEPENDENCIES $pkg_dep_name"
         fi