Add default_action param for rule-group

[celeronsx]

Hi! Cool module, but we need this also in the rule-group, could you add it? (Just dynamic default_action) and new variable)
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│ Error: Unsupported argument
│
│ on ../../modules/waf/rulegroup/main.tf line 9, in module "this":
│ 9: default_action = var.default_action
│
│ An argument named "default_action" is not expected here.
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