New feature: ability to delete CloudTrail trails

[TryTryAgain]

Likely related to https://github.com/gruntwork-io/cloud-nuke/issues/212 (although I didn't experience this issue in some quick recent tests; maybe the accounts/activity was too small) ...

But, I didn't see any feature request to add CloudTrail trails specifically. It would be very helpful to add the CloudTrail service to the list of supported services for cloud-nuke.