Cannot define fine grained user permissions

[sriramsub]

Nile currently supports user authentication and a very simple way to enforce permissions for users to the tenants they belong to. This is done by setting the nile.user_id env variable. If you use the Nile SDK, this is already done for developers. While this is great, Nile should support more fine-grained permissions for resources. This is to track user requests for this feature and feedback. The design proposal is tracked here https://github.com/orgs/niledatabase/discussions/160