ci(aio): convert deploy-staging to a shell script

aio/scripts/deploy-staging.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+# WARNING: FIREBASE_TOKEN should NOT be printed.
+set +x -eu -o pipefail
+
+
+FIREBASE_PROJECT_ID=aio-staging
+
+cd "`dirname $0`/.."
+
+# Build the app
+yarn build
+
+# Deploy to staging
+firebase use "$FIREBASE_PROJECT_ID" --token "$FIREBASE_TOKEN"
+firebase deploy --message "Commit: $TRAVIS_COMMIT" --non-interactive --token "$FIREBASE_TOKEN"
+
+cd -