IP/CIDR validation and parsing improvements

[danwinship]

Enhancement Description

• One-line enhancement description (can be used as a release note): Improvements to external validation and internal parsing of IP addresses and CIDR values.
• Kubernetes Enhancement Proposal:
• Discussion Link: Tighten IP/CIDR validation kubernetes#122550 and WIP utilip: use netip, improved IP/CIDR parsing, improved IP/CIDR utilities kubernetes#122549 have background; I am belatedly writing a KEP to centralize further discussion and because it will just be easier to track this work with a KEP.
• Primary contact (assignee): @danwinship
• Responsible SIGs: sig-network
• Enhancement target (which target equals to which milestone):
  • Alpha release target (x.y):
  • Beta release target (x.y):
  • Stable release target (x.y):
• Alpha
  • KEP (k/enhancements) update PR(s):
  • Code (k/k) update PR(s):
  • Docs (k/website) update PR(s):

Please keep this description up to date. This will help the Enhancement Team to track the evolution of the enhancement efficiently.

[danwinship]

/sig network
/assign