🚩(backend) add homepage feature flag

Add a homepage feature flag that we will
propagate to the frontend.
It will be used to enable or disable the
homepage at runtime.

src/backend/core/api/viewsets.py

@@ -1692,6 +1692,7 @@ class ConfigView(drf.views.APIView):
             "CRISP_WEBSITE_ID",
             "ENVIRONMENT",
             "FRONTEND_CSS_URL",
+            "FRONTEND_HOMEPAGE_FEATURE_ENABLED",
             "FRONTEND_FOOTER_FEATURE_ENABLED",
             "FRONTEND_THEME",
             "MEDIA_BASE_URL",