Lookup by endpoint should check IP and host

[mgravell]

Currently, only exact endpoint matches are considered. However, specially in the case of CLUSTER, a node may have both host and IP evidently. Further, -MOVED may return the unexpected option, leading to additional connections.

We should:

• record both identities as declared, for example from the CLUSTER NODES response
• if no equality endpoint match is found, check also using the best data available (after type-testing the endpoint)

Context: dotnet/aspnetcore#59211

Auxiliary consideration: should cluster routing be limited to IP, as current? Should there be a "use host routing" option? Or should we try IP and use host if that fails?