KMS Key Policy Scan double-counts duplicates

[zmarois]

My account has a KMS key that the KMS Key Policy plugin reports as having 13 users/roles allowed to use it. They key in question seems to have 3 policies, one with one user, another with 6 users, and a third with the same 6 users but different actions/conditions. I'd add that up to 7 instead of 13.

The code does not seem to deduplicate for each policy.