Add IPv6 environment testing workflow to ensure NGF works in IPv6-only environments

[salonichf5]

As an NGF User,
Is your enhancement request related to a problem? Please describe.

We occasionally encounter bugs reported by community members who operate clusters in IPv6-only environments. This arises because our current testing framework for NGF functionality is limited to dual-stack setups (IPv4 and IPv6). To address this gap, we need to design and implement a dedicated pipeline workflow to test NGF compatibility in IPv6-only environments and ensure robust functionality for such configurations.

What would you like to be added:
Add a IPv6 only environment in the pipeline to test NGF

Why this is needed:
To avoid future IPv6 bugs

Acceptance:

• The workflow configures an IPv6-only and is able to successfully send traffic.

[salonichf5]

Some more information for whoever picks it up

GitHub runners currently do not support IPv6. However, a recent update has introduced the ability to specify the network option for containers. This opens up the possibility of testing whether an IPv6-only environment can be successfully run within the pipeline.

After discussions with @sjberman, there seems to be two potential approaches for addressing this:

1. Kind Cluster Approach

• Create and configure a kind cluster that supports only IPv6 traffic.
• Install NGF with the option --set nginx.config.ipFamily=ipv6.
• Verify functionality by running this setup within the pipeline, installing NGF, and sending traffic through it.

2. GKE cluster + NFR Test Suite

• Configure a basic GKE cluster and virtual machine to facilitate testing.
• Install NGF with the option --set nginx.config.ipFamily=ipv6.
• Enable only IPv6 network in GKE cluster
• Verify functionality by running this setup within the pipeline, installing NGF, and sending traffic through it.
• Run this test as part of the NFR suite on a bi-weekly basis