Draft: network: replace custom Ipv[4,6]Address comparisons with default three-way comparison

Why?

Because otherwise I can't define 3-way comparison operators in classes using Ipv[4,6]Address.

Note: default comparison operators are great (unless you have member variables that don't need to be checked): https://en.cppreference.com/w/cpp/language/default_comparisons.html

... needs more work.