[aws:ses:debug] Debug topics and subscriptions

[Aerendir]

Is your feature request related to a problem? Please describe.
If Identities are subscribed to some SNS topics (and so, there are the corresponding subscriptions in SNS), ensure the topics exist.

If the topics don't exist, alert about this situation and inform that they should be created running the command aws:ses:configure.

When notification type is tracked, check the corresponding topic is subscribed. Ex.: If I activate the tracking for Bounces, the command has to check that a topic is subscribed to the notifications about Bounces. If I disable a tracking, the command has to check that no topic is subscribed for that type (requires #62 and of #69).