DRAFT: Add sni rewrite support

[Joey-Rose]

• Read the Contributing document.

Summary

1. Extracts SniRewriteSan from RouteSchema and includes it in config.Route
2. Extracts SniRewriteSan from config.Route and includes it in models.TcpRouteMapping struct in SniRewriteHostname field
3. Extracts SniRewriteHostname from models.TcpRouteMapping struct and includes it in BackendServerInfo struct
4. Extracts SniRewriteHostname from BackendServerInfo struct and includes it in BackendServerKey struct
5. Updates config_marshaller.go to add sni rewrite string if BackendServerKey.SniRewriteHost is populated

Backward Compatibility

Breaking Change?

No