[Feature] Kibana authentication on resource-level `kibana_connection`

[Zawadidone]

Is your feature request related to a problem? Please describe.
I would like to use the provider to create Kibana resources (elasticstack_kibana_*) on multiple Elastic Cloud cluster. But this is not supported for Kibana resources, because this can only be configured in the provider section using static credentials for a single Kibana instance.

https://registry.terraform.io/providers/elastic/elasticstack/latest/docs

provider "elasticstack" {
  kibana {
    username  = "elastic"
    password  = "changeme"
    endpoints = ["http://localhost:5601"]
  }
}

Each elasticsearch resource supports an elasticsearch_connection block, which allows the usage of the same provider on multiple Elasticsearch instances. I would like to have the same feature for Kibana resources.

Describe the solution you'd like
Add the kibana_connection block to every Kibana resource (elasticstack_kibana_*) which can be used by Terraform to connect with a Kibana instance:

resource "elasticstack_kibana_data_view" "default" {
  [...]

  kibana_connection {
    endpoints = [ec_deployment.default.kibana.https_endpoint]
    username  = ec_deployment.default.elasticsearch_username
    password  = ec_deployment.default.elasticsearch_password
  }
}

[romanlytovchenko]

But it is possible to configure few providers with aliases for different kibana instances, like this:

provider "elasticstack" {
  alias      = "kibana_1"
  kibana {
    username  = "elastic"
    password  = "changeme"
    endpoints = ["http://localhost:5601"]
  }
provider "elasticstack" {
  alias      = "kibana_2"
  kibana {
    username  = "elastic"
    password  = "changeme"
    endpoints = ["http://localhost:5601"]
  }
}

[Zawadidone]

This only supports a hardcoded provider configuration without the usage of variables. The values of the arguments username, password and endpoints are not known when writing the provider but are dependent on other resources like ec_deployment.