add helm test using curl

chart/templates/tests/curl.yaml

+---
+apiVersion: v1
+kind: Pod
+metadata:
+  name: {{ include "shibboleth-sp.fullname" . }}-helm-test-curl
+  annotations:
+    "helm.sh/hook": test
+spec:
+  containers:
+    # check apache is responding
+    - name: root
+      image: "cr.gitlab-int.switch.ch/maps/upstream-images/curlimages/curl:7.75.0"
+      command:
+        - "sh"
+        - "-c"
+        - |
+          curl --fail http://{{ include "shibboleth-sp.fullname" . }} -D /tmp/header.out -o /tmp/document.out
+          echo "### HEADER ###"
+          cat /tmp/header.out
+          echo "### DOCUMENT ###"
+          cat /tmp/document.out
+          echo "### TESTS ###"
+          grep "302 Found" /tmp/header.out
+          grep "Location: https://wayf.switch.ch/SWITCHaai/WAYF" /tmp/header.out
+    # check shibboleth is responding
+    - name: session
+      image: "cr.gitlab-int.switch.ch/maps/upstream-images/curlimages/curl:7.75.0"
+      command:
+        - "sh"
+        - "-c"
+        - |
+          curl --fail http://{{ include "shibboleth-sp.fullname" . }}/Shibboleth.sso/Session -D /tmp/header.out -o /tmp/document.out
+          echo "### HEADER ###"
+          cat /tmp/header.out
+          echo "### DOCUMENT ###"
+          cat /tmp/document.out
+          echo "### TESTS ###"
+          grep "200 OK" /tmp/header.out
+          grep "A valid session was not found." /tmp/document.out
+  restartPolicy: Never