Create an activation wizard to simplify activating an extension across all regions

[ericzbeard]

The instructions for activating an extension are quite complex, and must be repeated in each region and account where you want to use the extension.

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/registry-public.html?icmpid=docs_cfn_console

Let's work on a CLI wizard that asks the user questions, or maybe just have a quick option that uses sane defaults and creates the execution role for you.

cfn activate --type RESOURCE --type-name Some::Public::Type