Migrate to IPv6-native

[jayaddison]

Is your feature request related to a problem? Please describe.
Tasks could include, and are not limited to:

• Determining a suitable IPv6 allocation range to use from our ISP
• Migrating pods within the microservice cluster to an IPv6 range
  • Should the Kubernetes host node be public and/or routable?
  • Should the Kubernetes pods be public and/or routable?
• Migrating stateful services (opensearch, postgresql, squid) to use IPv6 addresses
• Updating haproxy, nginx configurations as-required
• Configuring production site network (routing, forwarding, and so on) as-required
• Adding IPv6 DNS records for *.reciperadar.com
• Testing connectivity from a range of source networks (cellular, IPv6 native, IPv4 native)

Describe the solution you'd like
Browsing to https://www.reciperadar.com should be possible from IPv6-based network environments, without the involvement of any IPv4-based networking.

IPv4 support may be retained if it proves straightforward to do that, but it isn't a goal of this migration.