Stealth/passive mode needed for iam__enum and other modules

[davidkutz-marks]

Certain modules, such as iam__enum_roles, attempt actions that will be logged by the target account(s) without first prompting the Pacu user, such as attempting to assume all enumerated roles cross-account. A stealth option will be added so that the Pacu user can add a flag and stop this behavior, making the entire enumeration passive from the target's perspective. (All activity for role enumeration affects the attacker's Cloudtrail only, not the target's.)

[DaveYesland]

Is this similar to #46? maybe they could be combined?