[Post-Demo] Refactor the infrastructure Terraform

[aplybeah]

Ticket

https://wicmtdp.atlassian.net/browse/PRP-117

Changes

• created network.tf
• add additional config to the ecr repo
• made additional resources more env-agnostic

Context for reviewers

After completing PRP-116: Migrate terraform for Eligibility Screener out of project repo and into Eligibility Screener repoREADY FOR REVIEW , we should refactor the terraform for the Eligibility Screener to use the same structure that we adopted for the PRP, based on the template repo.

Testing

When this is out of draft:

1. Run terraform plan
2. Plan should run successfully with no errors
3. Run terraform apply
4. No changes should be committed since all of the listed resources currently exist

additional testing:

1. Log into the demo console
2. navigate to Load Balancers
3. use the DNS name for the load balancer to navigate to the staging version of the demo
   • expected error: Certificate not Valid -> we don't have a friendly domain name for this new load balancer that this certificate would expect.
4. verify that other necessary resources such as security groups, etc exist in the console

[rocketnova]

@aplybeah I would recommend creating and deploying the entire thing from scratch in a new env to make sure everything works as expected.