Add ability to append a randomized suffix to all bucket names

[tpdownes]

Google Cloud Storage buckets need globally unique names. Therefore, it's helpful to have a randomized component to names, especially for use in example code. The following code

resource "random_id" "bucket" {
  byte_length = 2
}

module "example_bucket" {
  source     = "terraform-google-modules/cloud-storage/google"
  version    = "~> 2.1"
  project_id = var.project_id
  location   = var.region

  prefix = "myproject"
  names  = ["data-${random_id.bucket.hex}"]
  versioning = {
    "data" : true
  }
  storage_class = "REGIONAL"
  admins = [
    module.sa_example.iam_email
  ]
  depends_on = [
    module.project_services
  ]
}

results in an error

│ The "for_each" value depends on resource attributes that cannot be determined until apply, so Terraform cannot predict how many instances will be created. To work around this,
│ use the -target argument to first apply only the resources that the for_each depends on.

This is for well-understood reasons about terraform plan and iteration. The project-factory module is subject to similar uniqueness requirements and resolves this issue by creating a random resource inside the module. This PR imitates that solution closely in order to aid the user (and developers of examples) to automatically create unique buckets that remain identifiable by eye.

[comment-bot-dev]

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