🚀(helm) support Django Admin pages in ingress paths

Based on @rouja reco, I added a dedicated ingress to serve Django Admin
pages and Django statics. The admin route will be secured by the oauth proxy.

I simply copy/pasted the first ingress template, and adapted it.

src/helm/env.d/dev/values.desk.yaml.gotmpl

@@ -46,4 +46,6 @@ ingress:
   enabled: true
   host: desk.127.0.0.1.nip.io
 
-
+admin:
+  enabled: true
+  host: desk.127.0.0.1.nip.io

src/helm/env.d/staging/values.desk.yaml.gotmpl

@@ -75,3 +75,10 @@ ingress:
   annotations:
     cert-manager.io/cluster-issuer: letsencrypt-prod
 
+admin:
+  enabled: true
+  host: desk-staging.beta.numerique.gouv.fr
+  annotations:
+    cert-manager.io/cluster-issuer: letsencrypt-prod
+    nginx.ingress.kubernetes.io/auth-signin: https://oauth2-proxy-preprod.beta.numerique.gouv.fr/oauth2/start
+    nginx.ingress.kubernetes.io/auth-url: https://oauth2-proxy-preprod.beta.numerique.gouv.fr/oauth2/auth