Add dynamic rule_group_reference_statement block to attach custom rule groups

[surendhar-kodaikal-palani]

Description

Add dynamic rule_group_reference_statement block to attach custom rule groups which is not supported by the current module.

How was it tested ?

Ran validate, plan, and apply

      + rule {
          + name     = "rule-custom-api-allow"
          + priority = 7
          + override_action {
              + none {}
            }
          + statement {
              + rule_group_reference_statement {
                  + arn = "arn:aws:wafv2:us-west-2:******:regional/rulegroup/*******"
                }
            }
          + visibility_config {
              + cloudwatch_metrics_enabled = true
              + metric_name                = "rule-custom-api-allow"
              + sampled_requests_enabled   = true
            }
        }

[lberbel]

I needed it as well!

[Ohid25]

Part of the 4.0.0 release! Thank you for your contribution!