Add setup root users implementation

configs/crystal/configure-network/up.nu

@@ -26,7 +26,7 @@ def main [cfg] {
     create_hosts
 
     if $cfg.ipv6_loopback {
-        create_ipv6_loopback        
+        create_ipv6_loopback
     }
 
     info "Configured network"

configs/crystal/setup-root-user/up.nu

@@ -1,6 +1,7 @@
 let RUN_IN_CHROOT = true;
 # Applies all system changes of `setup-root-user`
 def main [cfg] {
-    echo "Executing up task `setup-root-user` with config" $cfg
-    todo "Implement setup-root-user"
+    debug $"Setting up root password ($cfg)"
+    run usermod --password $cfg.password root
+    info "Configured root user"
 }