feat!: (IAC-619) Support VPCs with private and control_plane subnets, NAT gateway is not required

[dhoucgitter]

Changes

• The nat_id input variable is now optional for BYO network scenarios 2 & 3
• Remove nat_id as a required input in BYOnetwork.md document for scenarios 2 & 3
• Update the nat_id note entry in CONFIG-VARS.md "Use Existing" table for nat_id entry to indicate when it is an optional input parameter
• When using the existing subnet_ids map, only two private subnet ids are always required to create the EKS cluster, public and database subnet_ids are optional for private subnet only configurations
• Add byo_network_scenario output variable value to terraform outputs to indicate which BYOnetwork scenario is driving IaC behavior
• Do not create new public or database subnet resources for BYON scenarios 2 & 3 when either public or database subnet_ids are not specified in existing subnets map
• Update VPC endpoint attributes to specify "Interface" or "Gateway" type, use private_dns_enable=true and add security group rule to allow access to AWS ECR container images from a private network
• Add vpc_private_access_cidrs and vm_private_access_cidrs, and default_private_access_cidrs configuration variables and add doc for them and existing cluster_endpoint_private_access_cidrs
• Add information regarding use cases for the private access CIDR variables in CONFIG-VARS.md

This update includes breaking changes and updates managed security groups and their rules. Existing EC2 instances and their network interfaces with references to the original security groups creates obstacles for direct replacement of those security groups. Users with infrastructure created with the v7.2.1 release or older will need to destroy their cluster using the version of viya4-iac-aws used to create their infrastructure and then recreate it with the latest release.

The current recommendation for users who want to use the release containing this PR and created their infrastructure for a Viya deployment with viya4-iac-aws:7.2.1 or earlier is to:

1. Follow the SAS Viya Platform Operation backup and restore documentation to perform a full backup of their environment.
2. Uninstall the SAS Viya deployment and destroy the infrastructure using the version of viya4-iac-aws you initially deployed with.
3. Recreate your infrastructure using the latest version of viya4-iac-aws
4. Follow the SAS Viya Platform Operation backup and restore documentation to restore your environment.

Tests

tests are being recorded in the internal ticket during testing

[thpang]

Looking for logic clarity

[thpang]

LGTM