Support custom OAuth parameters or configurable auth URL from frontend

Supabase Auth should support passing custom parameters (such as tenant, login_hint, or other provider-specific query params) to the OAuth authorization URL directly from the frontend. Alternatively, there should be a way to override or extend the generated auth URL at runtime on a per-login basis. Problem Currently, when using Supabase Auth’s OAuth providers (like Microsoft, Google, etc.), the redirect URL is fully managed by Supabase. While this works for most single-tenant cases, it limits flexibility for multi-tenant or dynamic login experiences. For example, with Azure AD, Supabase always sends users to: But for multi-tenant apps, users often belong to different Azure AD tenants, and should be redirected to: This tenant ID cannot currently be set from the frontend. Similarly, there’s no way to add parameters like login_hint (which improves user experience by pre-filling the email address). It can be set from the backend but this wont work for multi tenant apps th…