Add SocketAddress to NetworkTypes

[gjcairo]

Motivation

We need some concept of a socket (IPv4/IPv6) address.

Solves #41

Modifications

This type already existed in swift-http-server, but we want to centralise all currency types in their own module, so moving that type here.

[guoye-zhang]

Let's pull the IPAddress types from Containerization? https://github.com/apple/containerization/blob/main/Sources/ContainerizationExtras/IPAddress.swift

[guoye-zhang]

SocketAddress is the types of addresses that socket can connect to, and I wonder if that should be a concurrency since it's specific to the socket API. Also port should probably be separate from IP since it's specific to TCP and UDP.

[FranzBusch]

I think it is okay moving forward with this type for now but we should engage with the maintainer of https://github.com/swift-dns/swift-endpoint/tree/main once we are public.

Also port should probably be separate from IP since it's specific to TCP and UDP.

I agree with this though. Port should only come into play with SocketAddress or an Endpoint type and not IPAddress