Classify PAT in Topology

It is planned to use a cells prefix for PAT in Cells 1.0

To avoid encoding business logic in Router, propose having the router send the PAT to the Topology service to classify.

Proposal

1. The Topology Classify RPC returns the correct cell based on the value of the prefix.
2. The PAT value is RED data so this data must be handled securely by both the HTTP router, and the Topology service