🔧(addon) parametrize the frontend nginx configuration via a volume

Mount the nginx configuration used by the frontend image as a volume
so the default one can be overridden by a custom configuration at
deployment time.

Based on suggestions from @rouja to help parametrize the
configuration at deployment time.

src/helm/env.d/dev-dinum/values.meet.yaml.gotmpl

@@ -23,6 +23,9 @@ frontend:
     - name: outlook-addon-manifest
       configMap:
         name: outlook-addon-manifest
+    - name: frontend-nginx-config
+      configMap:
+        name: frontend-nginx-config
 
   extraVolumeMounts:
     - name: outlook-addon-config
@@ -33,6 +36,10 @@ frontend:
       mountPath: /usr/share/nginx/html/addons/outlook/manifest.xml
       subPath: manifest.xml
       readOnly: true
+    - name: frontend-nginx-config
+      mountPath: /etc/nginx/conf.d/default.conf
+      subPath: default.conf
+      readOnly: true
 
   outlookAddon:
     enabled: true
@@ -41,3 +48,6 @@ frontend:
     feedbackForm: "https://tests.com/"
     appName: "Visio"
     id: "a025f0f6-757a-4790-97f3-99c66c4a5795"
+
+frontendNginxConfig:
+  enabled: true

src/helm/env.d/dev-keycloak/values.meet.yaml.gotmpl

@@ -53,3 +53,6 @@ agentSubtitles:
         items:
         - key: cacert.pem
           path: cert.pem
+
+frontendNginxConfig:
+  enabled: false