site24x7_tag resource should export tag_id and other attributes returned by API endpoint

[andreub]

With following code example:

resource "site24x7_tag" "this" {
  tag_name = "pagerduty_service_id"
  tag_value = var.pagerduty_service_id
  tag_color = "#B7DA9E"
}

resource "site24x7_rest_api_monitor" "this" {
...
tag_ids = [
    "${site24x7_tag.this.tag_id}",
  ]
..
}

I'm getting the following error, even though API implementes it:

Error: Unsupported attribute

  on main.tf line 77, in resource "site24x7_rest_api_monitor" "this":
  77:     "${site24x7_tag.this.tag_id}",

This object has no argument, nested block, or exported attribute named
"tag_id".

Prevents us from using chained resources creation