Support for Multiple OAuth Providers in Connector Basic

As of today while using Connector Basic admins has to choose only one of the OAuth provider (either Github or google or discord etc) but only ONE. There is no provision for adding multiple OAuth providers.

This will give user a choice of logging in with the account they like.

Start by locating Connector Basic's OAuth provider configuration and login flow, then inspect how the current single-provider choice is stored and applied. Define how multiple providers should be configured and exposed, and verify that users can choose among GitHub, Google, Discord, and other supported providers.

Written by the indexing model from the issue text.