support CIDR and IPv6

[Prakhar-Shankar]

Problem:
Earlier the program was adding "/32" to every destination IP be it CIDR or IPv6.

Solution:
Introduced normalizeIPOrCIDR() to validate and normalize IPs:

• Plain IPv4 - /32
• Plain IPv6 - /128
• Valid CIDR - kept as-is
• Explicit errors on invalid IP/CIDR inputs.

fixes #717

Note - I have also added a test file to check everything is working fine.

Checklist:

• Fixes DESTINATION_IPS in network experiments don't support CIDR blocks #717
• PR messages has document related information
• Labelled this PR & related issue with breaking-changes tag
• PR messages has breaking changes related information
• Labelled this PR & related issue with requires-upgrade tag
• PR messages has upgrade related information
• Commit has unit tests
• Commit has integration tests
• E2E run Required for the changes

[Copilot]

Pull Request Overview

This PR adds support for CIDR blocks and IPv6 addresses in the pod network partition functionality. Previously, the system was incorrectly appending "/32" to all destination IPs regardless of their format.

• Introduces normalizeIPOrCIDR() function to properly handle IPv4, IPv6, and CIDR formats
• Replaces the previous IP processing logic with proper validation and normalization
• Adds comprehensive test coverage for the new functionality

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
network-policy.go	Implements new IP/CIDR normalization logic and refactors setExceptIPs method
network-policy_cidr_test.go	Adds unit tests for CIDR handling and IP normalization functionality

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[neelanjan00]

Hey @Prakhar-Shankar thanks for the PR 🙏, can you please address the Copilot comments?

[Prakhar-Shankar]

Hey @Prakhar-Shankar thanks for the PR 🙏, can you please address the Copilot comments?

Thanks for reviewing, I have changed the test file so that it won't take empty string as an error. I have also added the recommended comments.

[neelanjan00]

LGTM.