Support Egress IPAM Operator in OVN

1. Proposed title of this feature request: Egress IPAM Operator support for OVN
2. What is the nature and description of the request? Customers use SDN plugin on self-managed and managed clusters that allowed them to install SDN as network plugin. To manage egress IPs at pod or namespace level, they are using this operator uniformly across these OCP clusters. However, in the ROSA and OSD clusters, OVN is the default and only supported network plugin available from OCP 4.11. This blocks customers who want to use this egress IPAM operator across their hybrid/multi-cloud environments because their automation and tooling does not work consistently. 
3. Why does the customer need this? (List the business requirements here): They will need (more) time to migrate from egress IPAM operator or SDN plugin to use OVN plugin and OVN's way for managing egress IPs at namespace or pod level. Due to missing feature parity, customers are blocked. A support exception has been requested to use SDN plugin with OCP 4.13 or 4.14 in managed services (ROSA, OSD on AWS), which is not aligned with the ARB decision to invest in the OVN plugin. We will be able to retire the support exception only upon reaching feature parity, enabling customers to migrate from SDN to OVN plugin. 
4. List any affected packages or components. OVN, Egress IPAM Operator