Enable Port Name overrides on web-api-service

[ibrahimparvez2]

When deploying this chart with Istio ingress due to istio's convention which requires port names to be prefixed http- this subsequently results in needing to patch web-api-svc manifest post deployment.

Changes proposed in this pull request

This allows users to override the default names provided which eases the issues when using istio service mesh

Contributor Checklist

• Variables are documented in the README.md
• Which branch are you merging into?
  • master is for changes related to the current release of the concourse/concourse:latest image and should be good to publish immediately
  • dev is for changes related to the next release of Concourse (aka unpublished code on master in concourse/concourse)

Reviewer Checklist

This section is intended for the core maintainers only, to track review progress. Please do not
fill out this section.

• Code reviewed
• Topgun tests run
• Back-port if needed
• Is the correct branch targeted? (master or dev)