Copy settings from another instance when creating a new

[tbroden84]

WHY are these changes introduced?

When creating a new instance, add support to copy the settings from an already existing one. E.g. copy the same RabbitMQ config and definitions to the new instance.

Requires: https://github.com/84codes/customer-console/pull/204

Reference: #139

WHAT is this pull request doing?

New copy_settings argument block for cloudamqp_instance resource. Declare which other CloudAMQP instance and settings that should be copied. The supported settings that can be copied are, alarms, config, definitions, firewall, logs, metrics and plugins.

HOW can this pull request be tested?

Create a new instance and copy over settings from an older.

resource "cloudamqp_instance" "instance_02" {
  name                = "terraform-cloudamqp-instance-02"
  plan                = "squirrel-1"
  region              = "amazon-web-services::us-west-1"
  rmq_version         = "3.12.2"
  tags                = ["terraform"]
  copy_settings {
    subscription_id = var.instance_id
    settings = ["config", "definitions"]
  }
}

[dentarg]

Oh I actually noticed this back in January: https://gist.github.com/dentarg/6b9d00aaa358ea7e933061c7bead4321/revisions

I tried to discuss it in https://84codes.slack.com/archives/C025WBLMV/p1674655802289809

[tbroden84]

Yeah. We also have this old branch: 952638f
Together with the bug fix (if approved), was just easier to start over.