DO NOT MERGE PoC(2616): spike - k8s gateway-api - initial commit

[pasitconsulting]

Context

Poc of k8s API-Gateway product to replace nginx-controller

Changes proposed in this pull request

• basic terraform install of gateway-api
• basic terraform install of traefik controller
  enough to be able to rebuild quickly as required and demo the features of the product as part of PoC

Guidance to review

• currently available in dev cluster3 (traefik is running in gateway-api namespace)
• rebuild as follows:-

gateway-api is installed in its own root module which deploys via terraform-apply from makefile, after terraform_aks_cluster module and before terrsform_kubernetes module

on any existing dev cluster:-

make development terraform-gateway-api-apply ENVIRONMENT=clusterN
make development terraform-kubernetes-apply ENVIRONMENT=clusterN

or for a full clean dev cluster install, just

make development terraform-apply 

welcome-app should be available:-
curl -I https://welcomeapp-gatewayapi.cluster3.development.teacherservices.cloud/

ITT:-
follow instructions on below PR to apply the HTTPRoute and test via the api-gateway:-
DFE-Digital/itt-mentor-services#1887

Checklist

• I have performed a self-review of my code, including formatting and typos
• I have cleaned the commit history
• I have added the Devops label
• I have attached the pull request to the trello card