Feature Request: Add support for Dedicated Coordinator Nodes

[ErezWeiss]

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 ✅: hashicorp/aws provider version v5.90.0.

Is your request related to a problem? Please describe.
The module does not support configuring dedicated coordinator nodes, a feature now available in AWS OpenSearch and supported by the aws_opensearch_domain resource.

Describe the solution you'd like.
Please add module variables for dedicated_coordinator_enabled, dedicated_coordinator_count, and dedicated_coordinator_type and pass them to the cluster_config block of the aws_opensearch_domain resource.

Describe alternatives you've considered.
The only alternative is to not use this module and define the aws_opensearch_domain resource manually, which loses the module's benefits.

Additional context
The arguments were added in v5.48.0 of the AWS provider:

cluster_config.dedicated_coordinator_enabled

cluster_config.dedicated_coordinator_count

cluster_config.dedicated_coordinator_type

[magreenbaum]

Dedicated coordinator node is currently supported by the module:

• terraform-aws-opensearch/main.tf

  Lines 132 to 149 in daec5aa

  	dynamic "node_options" {
  	for_each = try(cluster_config.value.node_options, [])
  	content {
  	dynamic "node_config" {
  	for_each = try([node_options.value.node_config], [])
  	content {
  	count = try(node_config.value.count, null)
  	enabled = try(node_config.value.enabled, true)
  	type = try(node_config.value.type, null)
  	}
  	}
  	node_type = try(node_options.value.node_type, node_options.key, null)
  	}
  	}

• Ex:

  terraform-aws-opensearch/examples/complete/main.tf

  Lines 67 to 75 in daec5aa

  	node_options = {
  	coordinator = {
  	node_config = {
  	enabled = true
  	count = 3
  	type = "m6g.large.search"
  	}
  	}
  	}

But the arguments to specify them as dedicated_coordinator_enabled, dedicated_coordinator_count, and dedicated_coordinator_type is not currently supported by the provider. There is an open issue for that upstream though:

• OpenSearch: Model dedicated coordinator nodes as regular fields instead of nested block hashicorp/terraform-provider-aws#42210