Refactor module interface for simplified IAM

[bharathkkb]

We should consider revamping the root module interface now that Terraform has support for module for_each to support a single bucket and any arbitrary bucket IAM roles, so we don't have a bool flag, map for each bucket and list for all buckets per bucket IAM role.

[github-actions]

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 7 days