Add kustomization.yaml for cert-manager with custom DNS settings

- Introduced a new kustomization.yaml file for cert-manager.
- Configured a patch to modify the cert-manager Deployment to use a custom DNS policy and settings.
- Set dnsPolicy to None and specified custom nameservers and search options.

cert-manager/upstream/kustomization.yaml

@@ -0,0 +1,30 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+  - cert-manager.yaml
+patches:
+  - target:
+      kind: Deployment
+      name: cert-manager
+      namespace: cert-manager
+    patch: |-
+      apiVersion: apps/v1
+      kind: Deployment
+      metadata:
+        name: cert-manager
+        namespace: cert-manager
+      spec:
+        template:
+          spec:
+            dnsPolicy: None
+            dnsConfig:
+              nameservers:
+                - "1.1.1.1"
+                - "8.8.8.8"
+              searches:
+                - cert-manager.svc.cluster.local
+                - svc.cluster.local
+                - cluster.local
+              options:
+                - name: ndots
+                  value: "5"