Revert "Drop unrelated privileged heredoc scanner"

This reverts commit 4c23077f80.

test/shell.d/fixtures/privileged-heredoc/safe-herestring.sh

@@ -0,0 +1,7 @@
+resolved="RemoteCommand none"
+
+grep -qvi '^remotecommand none$' <<<"$resolved" || true
+
+sudo tee /etc/omarchy/plain.conf >/dev/null <<'EOF'
+ok=1
+EOF