uefi-raw: move types to new net module, improve convenience

[phip1611]

This prepares my vision for #1575, a split-out from #1645, and a change to uefi-raw in the sense that some types now have slightly more higher-level logic. This "higher-level" logic is still low-level enough that I think it is perfectly fine to keep it. It will also not hinder Rust-based UEFI implementations.

TL;DR: My vision is that in uefi we only expose core::net::{IpAddr, Ipv4Addr, Ipv6Addr} and protocol implementations can use From/Into to do all the necessary work under the hood.

Let me know what you think!

List of Changes

• refactored the IpAddress type to be more convenient, more memory-safe, and pleasant to use
• added lots of convenient From implementations

Checklist

• Sensible git history (for example, squash "typo" or "fix" commits). See the Rewriting History guide for help.
• Update the changelog (if necessary)

[phip1611]

For the record. Starting Friday, I'll be on vacation until July 30th. My plan is to program-detox for the whole period 😀 Restarting the work afterwards

[phip1611]

I'm unsure how I could fix the rustdoc error best. I want the documentation of the net module to be publicly available (it is a clear value-add), but earlier you suggested exporting its exports in a flat way, i.e., directly from the top-level.

However: making the module public allows to import the same types from uefi_raw::Type and uefi_raw::net::Type, which is not ideal. Perhaps we should export all net::* types also publicly?