systemd: port to Go, and read a system unit's journal as root

The journal verb ran journalctl as the operator account, which outside the
journal's group sees only its own entries: every system service read
'-- No entries --', and a person reached for a shell. The read now
escalates with sudo -n like the acts; ported to Go with every test. hq
issue 255.

modules/systemd/module.json

@@ -29,9 +29,12 @@
       {
         "name": "tools",
         "kind": "bundle",
-        "language": "typescript",
-        "entrypoints": [
-          "tools/index.js"
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/systemd-tools",
+        "binary": "systemd-tools",
+        "loads": [
+          "systemd-tools"
         ]
       }
     ]