Poc/waf v4.x

[shaun-nx]

Proposed changes

Changes:

1. Updates to Dockerfile to pull from the pkgs-test repo. Changes taken configurable plus repo #5013 for testing

Example build command:

make debian-image-plus TARGET=local TAG=r32-test PREFIX=nginx-plus-ingress PLUS_REPO=pkgs-test.nginx.com

What's working:

• Build NIC with the latest v4 version of NAP (set NGINX_PLUS_VERSION=R31 in Dockerfile first)

What's not working

• Build v4 NAP with R32 of NIC from the preview repo.

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[shaun-nx]

Closing as changes were added in #5649