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.

首先定位 Connector Basic 的 OAuth 提供商配置和登录流程，然后检查当前单一提供商的选择是如何存储和应用的。定义应如何配置和公开多个提供商，并验证用户可以在 GitHub、Google、Discord 和其他受支持的提供商之间进行选择。

由索引模型根据 Issue 内容生成。