grafana-watcher: allow credentials from env variable

hack/scripts/generate-grafana-credentials-secret.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+if [ "$#" -ne 2 ]; then
+    echo "Usage: $0 user password"
+    exit 1
+fi
+
+user=$1
+password=$2
+
+cat <<-EOF
+apiVersion: v1
+kind: Secret
+metadata:
+  name: grafana-credentials
+data:
+  user: $(echo -n ${user} | base64 --wrap=0)
+  password: $(echo -n ${password} | base64 --wrap=0)
+EOF
+