Support certificates configuration in TLSStore CRD

Co-authored-by: Romain <rtribotte@users.noreply.github.com>

pkg/provider/kubernetes/crd/fixtures/with_tls_store_certificates.yml

@@ -0,0 +1,43 @@
+apiVersion: traefik.containo.us/v1alpha1
+kind: TLSStore
+metadata:
+  name: default
+  namespace: default
+
+spec:
+  certificates:
+    - secretName: supersecret
+
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: supersecret
+  namespace: default
+
+data:
+  tls.crt: LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCi0tLS0tRU5EIENFUlRJRklDQVRFLS0tLS0=
+  tls.key: LS0tLS1CRUdJTiBQUklWQVRFIEtFWS0tLS0tCi0tLS0tRU5EIFBSSVZBVEUgS0VZLS0tLS0=
+
+---
+apiVersion: traefik.containo.us/v1alpha1
+kind: IngressRoute
+metadata:
+  name: test.route
+  namespace: default
+
+spec:
+  entryPoints:
+    - web
+
+  routes:
+  - match: Host(`foo.com`) && PathPrefix(`/bar`)
+    kind: Rule
+    priority: 12
+    services:
+    - name: whoami
+      port: 80
+
+  tls:
+    store:
+      name: default