terraform to create an Azure policy to validates Resource Group Names using name pattern

I am trying to create an Azure policy which I can assign at the subscription level, and control the naming of the resource groups in the subscription.

What resource type (or other method) can I use to limit my validation to the resource group name only?

and also i need to use it for management group to create name policy using terraform

resource "azurerm_policy_definition" "policy" {
  name         = "PaC-Naming-Convention02rgAll"
  policy_type  = "Custom"
  mode         = "All"
  display_name = "PaC_Naming_Convention01All"

  metadata     = <<METADATA
    {
    "category": "Demo"
    }
  METADATA

  policy_rule = <<POLICY_RULE
    {
    "if": {
        "allOf":[
            {
                "not":{
                    "field":"name",
                    "match":"[parameters('namePattern')]"
                }
            },
            {
                "field": "type",
                "equals": "Microsoft.Resources/subscriptions/resourceGroups"
            }
        ]
    },
    "then": { 
      "effect": "deny"
    }
  }
POLICY_RULE

  parameters = <<PARAMETERS
    {
        "namePattern":{
            "type": "String",
            "metadata":{
                "displayName": "namePattern",
                "description": "? for letter, # for numbers"
            }
        }
  }
PARAMETERS
}

data "azurerm_subscription" "current" {
}

# Define Azure Policy Assignment
resource "azurerm_policy_assignment" "policy-assignment" {
  name                 = "Naming-Convention-Assignment02All"
  scope                = data.azurerm_subscription.current.id
  policy_definition_id = azurerm_policy_definition.policy.id
  description          = "Naming convention"
  display_name         = "Naming-Convention-AssignmentAll"

  parameters = <<PARAMETERS
{
  "namePattern": {
    "value": "rg-?????-###"
  }
}
PARAMETERS
}