update upstreams to format ipv6 adddress for nginx plus

[salonichf5]

Proposed changes

Problem: Users want to have IPv6 upstreams correctly formatted when using NGINX Plus with NGF.

Solution: Adds a fix to update IP format based on endpoint type.

Testing: Manual Testing of installing NGF with NGINX Plus and verifying config for IPv6 services.

nginx.conf

upstream default_tea_80 {
    random two least_conn;
    zone default_tea_80 1m;

    server 192.168.194.32:8080;
}

upstream default_coffee_80 {
    random two least_conn;
    zone default_coffee_80 1m;

    server [fd07:b51a:cc66:a::1f]:8080;
}

Curl request using IPv6 address for IPv6 service

curl -v --resolve cafe.example.com:$GW_PORT:$GW_IPv6  http://cafe.example.com:$GW_PORT/coffee
* Added cafe.example.com:8080:::1 to DNS cache
* Hostname cafe.example.com was found in DNS cache
*   Trying [::1]:8080...
* Connected to cafe.example.com (::1) port 8080
> GET /coffee HTTP/1.1
> Host: cafe.example.com:8080
> User-Agent: curl/8.4.0
> Accept: */*
>
Handling connection for 8080
< HTTP/1.1 200 OK
< Server: nginx
< Date: Wed, 07 Aug 2024 04:22:19 GMT
< Content-Type: text/plain
< Content-Length: 170
< Connection: keep-alive
< Expires: Wed, 07 Aug 2024 04:22:18 GMT
< Cache-Control: no-cache
<
Server address: fd07:b51a:cc66:a::1f:8080
Server name: coffee-6b8b6d6486-whg5r
Date: 07/Aug/2024:04:22:19 +0000
URI: /coffee
Request ID: cb0e68d5b46bb6876d36d3ece0447724

Curl request using IPv4 address for IPv6 service

curl -v --resolve cafe.example.com:$GW_PORT:$GW_IP  http://cafe.example.com:$GW_PORT/coffee
* Added cafe.example.com:8080:127.0.0.1 to DNS cache
* Hostname cafe.example.com was found in DNS cache
*   Trying 127.0.0.1:8080...
* Connected to cafe.example.com (127.0.0.1) port 8080
> GET /coffee HTTP/1.1
> Host: cafe.example.com:8080
> User-Agent: curl/8.4.0
> Accept: */*
>
Handling connection for 8080
< HTTP/1.1 200 OK
< Server: nginx
< Date: Wed, 07 Aug 2024 04:22:09 GMT
< Content-Type: text/plain
< Content-Length: 170
< Connection: keep-alive
< Expires: Wed, 07 Aug 2024 04:22:08 GMT
< Cache-Control: no-cache
<
Server address: fd07:b51a:cc66:a::1f:8080
Server name: coffee-6b8b6d6486-whg5r
Date: 07/Aug/2024:04:22:09 +0000
URI: /coffee
Request ID: 34eeff12748cdac848d5a8db5c1345b4

Please focus on (optional): If you any specific areas where you would like reviewers to focus their attention or provide
specific feedback, add them here.

Closes #2338

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

Release notes

If this PR introduces a change that affects users and needs to be mentioned in the release notes,
please add a brief note that summarizes the change.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.07%. Comparing base (2cb44de) to head (4b60de0).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2339   +/-   ##
=======================================
  Coverage   88.07%   88.07%           
=======================================
  Files          97       97           
  Lines        6993     6996    +3     
  Branches       50       50           
=======================================
+ Hits         6159     6162    +3     
  Misses        777      777           
  Partials       57       57           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.