[K9VULN-9412] [K9VULN-9413] docs(gcp): add gcp tf examples

[mohamed-challal]

What?

• add TF examples for single region (simple), and cross project multi region (advanced)

[k3nz0]

Got an error when trying to apply this terraform

╷
│ Error: Invalid count argument
│
│   on .terraform/modules/datadog_agentless_scanner/gcp/modules/vpc/main.tf line 6, in resource "random_id" "deployment_suffix":
│    6:   count       = var.unique_suffix == "" ? 1 : 0
│
│ The "count" 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 count depends on.

I fixed it by adding this here + passing the unique_suffix variable in main.tf (module datadog_agentless_scanner):

variable "unique_suffix" {
  description = "Unique suffix to append to resource names. Must be alphanumeric only and maximum 6 characters (will be appended with region suffix)."
  type        = string
  default     = "foobar"
}

[mohamed-challal]

This should fix the issue with TF plan
[K9VULN-8670] fix(gcp): fix gcp terraform plan

[mohamed-challal]

I merged the examples and the documentation.
We continue to iterate in other PRs.
Thanks for the reviews!