Background context:

Submariner is transparent for Istio when it is responsible only for providing single network in a multi-cluster mesh deployment. Submariner is also a MCS controller (when it's deployed with Lighthouse), and then Istio could rely on ServiceExport and ServiceImport resources to manage service discovery and traffic control. However, this requires enabling MCS_* feature flags.

This epic aims to verify, test, document and potentially fix the MCS_* feature flags supported by Istio.