Warn when ReachableAddresses restricts connections to relays chosen by others

Tor clients which use one-hop paths to access relays chosen by other clients can't use ReachableAddresses (or similar options) or ClientUseIPv4 0 (#17840 (moved)). If they did, this would deny them access to some relays, potentially impairing functionality or performance.

This affects the following Tor modes:

• Tor2Web - Introduction Points
• RSOS - Rendezvous Points

For directory, guard, and bridge connections, clients choose or are configured with accessible relays based on ReachableAddresses / ClientUseIPv4/ClientUseIPv6.