CI-CD for domains

[neillturner]

Context

adding workflows for domain deployment to build workflows

Changes proposed in this pull request

updated deploy.yml adding calls to the deploy domains github actions.
output.tf is added to provide external_urls for testing
updated Makefile to make domains-plan work for different environments

Guidance to review

checkout branch and run the following

make qa_aks domains-plan 
make staging_aks domains-plan 
make sandbox_aks domains-plan 
make production_aks domains-plan 

make domains-infra-plan

verify the external urls are correct.

in browser check health check url

https://www.apply-for-teacher-training.service.gov.uk/health`

verify the code in the github action
verify the list of domain_environments is correct

Link to Trello card

Implement CI/CD for domains on all services