envoy-gateway: add seerr-test.jsme.be listener + cert (OIDC preview test)

Temporary listener/cert for the seerr-test instance running the
preview-new-oidc build. Remove along with the seerr-test workload when
testing is done.

envoy-gateway/seerr/test-certificate.yaml

@@ -0,0 +1,14 @@
+apiVersion: cert-manager.io/v1
+kind: Certificate
+metadata:
+  name: seerr-test-tls
+  namespace: envoy-gateway
+spec:
+  secretName: seerr-test-tls
+  privateKey:
+    rotationPolicy: Always
+  issuerRef:
+    name: azure-dns
+    kind: ClusterIssuer
+  dnsNames:
+    - seerr-test.jsme.be