Hardcoded `GhostbusterTargetAccountRole` makes it difficult for Control Tower users

[nmasur]

Hey, thanks for this great project! I want to use this tool with AWS Control Tower with all the accounts in the organization. One of the features of Control Tower is that every account gets an aws-controltower-ReadOnlyExecutionRole which can be assumed by Lambda functions in the Audit account.

There is an option for setting the name of the role to assume in a CSV file, but I won't have that in a Lambda function, and we want to use the autorole. Currently, when using the autorole, the name of the role assumed in each account is hardcoded to GhostbusterTargetAccountRole.

Ideally, we would make this an input option so that we could use aws-controltower-ReadOnlyExecutionRole or any other role that sits in each of the accounts. Thanks!