Avoid assuming relays have a single IPv4/IPv6 address
Many areas of the Tor codebase assume that a relay has a single IPv4 address, or perhaps an IPv4 and an IPv6 address. Multi-homed relays may have many such addresses.
Therefore, some callers of get_interface_address[6] may be able to use the list of addresses from the get_interface_address6_list function introduced in #17027 (moved).
We should review all calls to get_interface_address and get_interface_address6 to see if they would benefit from using a list instead.
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