Registry: add support for TLS on the Pod service

What does this MR do?

Enable configuration and use of TLS on the registry pods.

registry:

• Implement configuration of http.tls per documenation
• Place TLS certificates
• Configure NGINX Ingress annotations where appropriate
• Update Deployment / Service with port.name of https when enabled

gitlab/*:

• Update implementation of gitlab.registry.api.* to ensure handling of scheme/protocol
• Piggy-back on existing global.hosts.registry.* settings as documented in https://docs.gitlab.com/charts/charts/globals#configure-host-settings

To enable:

global:
  ## add signing CA to all pods
  certificates:
    customCAs:
    - secret: services-internal-tls-ca
  ## tell generation mechanisms to use https
  hosts:
    registry:
      protocol: https

registry:
  ## configure TLS
  tls:
    enabled: true
    secretName: services-internal-tls
    ## configure Ingress to verify the TLS on the backend
    verify: true
    caSecretName: default/services-internal-tls-ca

TODO

• Documentation
• RSpec

Related issues

Closes #3398 (closed)

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