Add a binary for generating the stats of the index

1) how many kinds of objects are being customized?
2) how many times is every kind of object customized?
3) how many kustomization features are being used?
4) how many times is every kustomization feature used?

api/internal/crawl/config/crawler/kustomize_stats/job.yaml

@@ -0,0 +1,20 @@
+apiVersion: batch/v1
+kind: Job
+metadata:
+  name: kustomize-stats
+spec:
+  template:
+    spec:
+      restartPolicy: OnFailure
+      containers:
+      - name: kustomize-stats
+        image: gcr.io/haiyanmeng-gke-dev/kustomize_stats:v1
+        imagePullPolicy: Always
+        command: ["/kustomize_stats"]
+        args: ["--kinds=50", "--identifiers=50", "--kustomize-features=50"]
+        env:
+        - name: ELASTICSEARCH_URL
+          valueFrom:
+            configMapKeyRef:
+              name: elasticsearch-config
+              key: es-url

api/internal/crawl/config/crawler/kustomize_stats/kustomization.yaml

@@ -0,0 +1,3 @@
+resources:
+- ../base
+- job.yaml