🔧(backend) add CRISP_WEBSITE_ID setting

Add setting CRISP_WEBSITE_ID. This setting is
used to configure the Crisp chat widget.
It will be available to the conf endpoint, to
be used by the frontend.

src/backend/core/api/viewsets.py

@@ -902,6 +902,7 @@ class ConfigView(views.APIView):
         """
         array_settings = [
             "COLLABORATION_SERVER_URL",
+            "CRISP_WEBSITE_ID",
             "ENVIRONMENT",
             "FRONTEND_THEME",
             "MEDIA_BASE_URL",