Feature to support for AWS OpenSearch private network

[alexanderogorodnikov]

Is your request related to a new offering from AWS?

Is this functionality available in the AWS provider for Terraform? See CHANGELOG.md, too.

• Yes ✅: The resource opensearch_domain is available since v.5.0.0 of aws provider: https://github.com/hashicorp/terraform-provider-aws/releases/tag/v5.0.0

Is your request related to a problem? Please describe.

When working AWS VPC module, private_subnets can be used for AWS EKS service for example.
What if same VPC has to be used for other AWS service like AWS OpenSearch? I cannot use same private network for both EKS and OpenSearch. There is already a support for Database and Elasticache. Support of OpenSearch can extend the capacities of this module.

Describe the solution you'd like.

1. Add support of OpenSearch private subnets to the module
2. Add OpenSearch route tables
3. Add other resources like NAT gateway, tags, ipv6 and all other necessary network resources for OpenSearch integration.

Describe alternatives you've considered.

Create custom VPC module with support of OpenSearch, may be, huh =)
Use intra_subnet for this purpose

Additional context

[alexanderogorodnikov]

I can add this feature