allow binding to an interface instead of an IP address

[arilotter]

Magicsock::listen currently supports either listening on a specific ipv4 and/or ipv6 address. However, binding to 0.0.0.0, either via None or passing that explicitly, will cause it to bind across multiple interfaces.

I have a use-case where I want to force Iroh connections through one or more specific network interface(s). My only option right now is to first query those interface(s) for their IP address(es), and then pass one of them to Magicsock.

Therefore, I currently cannot bind on two interfaces (both v4 or v6) while avoiding a third.

I would love the ability to bind to an arbitrary list of interfaces, each on v4, v6, or both.