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

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`