Add HAProxy as an option for ingress controller provider

What does this MR do?

Adds HAProxy Ingress Controller as an option to replace NGINX.

Related issues

Related to https://gitlab.com/gitlab-org/charts/gitlab/-/issues/3251

Related to !2539 (merged)

Related to #3442 (closed)

Testing

1. Install the chart:

   helm upgrade --install gitlab . -n gitlab -f examples/values-haproxy-ingress.yaml

2. Test access to endpoints:

   • gitlab.yourdomain.com
   • minio.yourdomain.com

3. Test git over SSH:

   1. Add SSH key to instance
   2. Create a project with a README
   3. Clone the project over SSH

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened