Add ATVM systemd runner service

atvm/watcher-service/cancel-atvm-runner.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+usage() {
+  cat <<'EOF'
+Usage:
+  cancel-atvm-runner.sh --build-name <name>
+EOF
+}
+
+BUILD_NAME=""
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --build-name) BUILD_NAME="${2:-}"; shift 2 ;;
+    -h|--help) usage; exit 0 ;;
+    *) echo "Unknown argument: $1" >&2; usage >&2; exit 1 ;;
+  esac
+done
+
+if [[ -z "$BUILD_NAME" ]]; then
+  echo "--build-name is required" >&2
+  usage >&2
+  exit 1
+fi
+
+systemctl stop "atvm-runner@${BUILD_NAME}.service" || true