s3-credentials delete-user command

[simonw]

I wanted to clean up all of the users and buckets I made while testing this tool.

Deleting buckets is easy enough with the aws s3 tool:

aws s3 rb s3://simonw-test-bucket-10 --force

Deleting users is harder:

aws iam delete-user --user-name s3.read-only.simonw-test-bucket-11
An error occurred (DeleteConflict) when calling the DeleteUser operation:
Cannot delete entity, must delete policies first.

I'm going to build a s3-credentials delete-user command which deletes the inline policies first.