Allow blocked user to use OAuth

What does this MR do and why?

Close https://jihulab.com/gitlab-cn/gitlab/-/issues/4566

允许 Blocked 状态下的用户正常使用 OAuth2，以支持官网建设新的账号体系。具体开放了以下权限：

1. 允许登录
2. 允许使用 OAuth2 功能
3. 允许调用用户信息 API /api/v4/user

此改动仅在以下条件下生效：

• Jihulab.com
• 极狐GitLab 自建的 OAuth App（重定向地址域名匹配 *.gitlab.cn）

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Before	After

How to set up and validate locally

1. GITLAB_SIMULATE_SAAS=1 gdk restart

2. 在 Admin Application 页面创建 OAuth2 App（勾选 read_user，回调地址的域名必须为 gitlab.cn ）

   

3. 在 Admin 页面对用户 A 进行 Block

   

4. 使用用户 A 的身份通过 OAuth2 获取用户信息，期待取到用户信息。大致步骤如下：
   4.1 GET http://127.0.0.1:3000/oauth/authorize?client_id={CLIENT_ID}&redirect_uri=https://gitlab.cn/&response_type=code&scope=read_user
   4.2 POST http://127.0.0.1:3000/oauth/token with code
   4.3 POST http://127.0.0.1:3000/api/v4/user with token

   

OAuth2 各个步骤详细请求参数如下：Gitlab_OAuth.postman_collection.json