Add Optional Helm Install Support

[bobbyiliev]

Similar to the AWS module PR here: MaterializeInc/terraform-aws-materialize#15

Uses the unified Helm chart terraform module: github.com/MaterializeInc/terraform-helm-materialize?ref=v0.1.0

• Introduced support for enabling Helm installation using:

  install_materialize_operator = true

• Added configuration for Materialize instances with optional instance-specific details, such as namespace, database credentials, and host. Example:

 materialize_instances = [
   {
     name           = "analytics"
     namespace      = "materialize-environment"
     database_name  = "analytics_db"
     cpu_request    = "2"
     memory_request = "4Gi"
     memory_limit   = "4Gi"
   },
   {
     name           = "production"
     namespace      = "materialize-environment"
     database_name  = "production_db"
     cpu_request    = "4"
     memory_request = "8Gi"
     memory_limit   = "8Gi"
   }
 ]

One thing to keep in mind is that the materialize_instances are using the kubernetes_manifest resource which has a couple of limitations:

• It requires the Kubernetes cluster to be running, otherwise it will fail to connect during the plan stage
• For CRDs it requires the operator to be installed in the cluster first, otherwise it will fail during the plan stage

The workaround for the above is to not define the materialize_instances initially, once the EKS cluster is ready along with the operator installed, then you can do a second run to setup the materialize_instances.