Simplified Authentication, Public Access and Roles

[andyslack]

Hi Guys,

In release v1.18.0 we have made some large refactors to our code to simplify and improve the authentication logic.

Authentication now works as follows on each endpoint, if failing, it will continue to the next stage:

1. Check if the table is open to the public via the _llana_public_tables and ensure the endpoint matches the access_level granted
2. Check if the database is open via the SKIP_AUTH .env flag
3. Authenticate the user
4. Performs the role-based checks via the llana_roles table

I have dropped support for _llana_auth, which was confusing to administrate and handle via our codebase.

I have introduced the allowed_fields option for role-based support, which allows you to specify which fields can be returned to users based on their role.

I added many more tests around role-based permissions to ensure they are respected.