Complex authorization methods implementation - Create a db_post_request Hook for Dynamic Data Masking in Supabase

Problem Currently, there is no mechanism in Supabase to dynamically mask or manipulate output data before it is sent to the client. While Row-Level Security (RLS) and Column-Level Security (CLS) provide robust access control, certain complex authorization scenarios remain challenging to implement securely without resorting to external middleware or duplicating logic. For example, when fetching a list of users, the desired behavior might be: • For users with the role customer: - Display the email field only if the user_id matches the authenticated user. - For other users, display NULL in the email field. • For users with the role admin: - Display all email fields without restriction. Achieving this securely is challenging due to: 1. Views: While it's possible to create a masking view, an attacker with access token could potentially bypass this by querying the base table directly. 2. Custom Edge Functions: Implementing complex rules via Edge Fu…