Force direct/relay connection

[ubuntuegor]

Use cases:

• On a bad local network direct connection may be too slow, user wants to force relay usage.
• User doesn't want to expose their IP address - force relay.

Not sure if forcing direct connection is useful - Magic Wormhole already prefers it and only falls back to the relay when a direct connection is not available, so forcing it will just make transfer less reliable.

https://docs.rs/magic-wormhole/0.8.0/magic_wormhole/transit/struct.Abilities.html