Add Terraform and Nixops deployment files

[bolt12]

Note: Please read the README for a thorough guide line on the whole deployment process.

This PR refurbishes the current deployment process of IOHK's networking team. Brief summary of the highlights:

• All machines should now run NixOS. This is going to be good to have a higher level of detail while managing the OS configuration; we are going to have rollbacks and cached builds, not to mention higher reproducibility and more flexibility when managing different versions of cardano-node.
• Automated AWS instances deployment with Terraform. Eventually this part of the process can be absorbed into either Nixops or vice-versa.
  • Currently due to the current situation with NixOS AMIs in the regions we want to launch nodes (which has already been patched), we need to upload our own NixOS images to these regions. The current Terraform deployment process is capable of handling that, although it should be just a matter of time before we can remove this from the process.
• Automated NixOS deployments to AWS instances with NixOps. This allows us to quickly monitorize, maintain and deploy fined-tuned NixOS configurations to our NixOS machines. We are able to declaratively start two instances of cardano-node (1 mainnet and 1 testnet) and customize, if needed, each one.

As one could understand the deployment process consists on 2 phases: Terraform deployment and Nixops deployment. The Terraform deployment process depends on a particular patch of this script file which is not included in this PR because one would have to fork the entirety of the Nixpkgs repository to do so. A better solution would be to clone the repository and apply the patch locally in the machine that is going to perform the deployment. This is needed for the reasons mentioned above and detailed in the README.

[bolt12]

closes IntersectMBO/ouroboros-network#3763

[bolt12]

In terraform run:

terraform show -json | jq '.values.root_module.child_modules[].resources[].values | "\(.availability_zone) : \(.public_ip)"' | grep -v "null : null"

to a file and import it here

[bolt12]

unfortunately I don't think this can be done reliably due to the existence of availability zones. For example the output of the command above looks something like:

"af-south-1b : ..."
"us-west-1c : ..."
"eu-west-3c : ..."
"us-east-2c : ..."
"ap-southeast-2c : ..."
"ap-southeast-1a : ..."
"sa-east-1c : ..."
"ap-northeast-1d : ..."

so there's information about the Region + Availability Zone and from what I gathered these are logical and can depend from user to user. So I am not sure these can change throughout the time.