前端功能实现：注册、登陆、展示用户信息、更改用户信息

[TremblingV5]

Link to an issue

What

1. 对后端代码的一点点修缮
2. 前端实现：注册、登陆、展示用户信息、修改用户信息

更改用户信息目前只做了更改用户名，更新用户头像的功能后续和上传视频一起做，封装成一个组件。

主流程可以跑通，前端样式后续再做调整

How

Screenshots

How to test

Checklist

• [ ] Link to an issue if it really related.
• [ ] At least describe what this PR does.
• [ ] Use rebase to confirm that current branch doesn't conflict with main branch.
• [ ] Unit tests. At least do not reduce the unit test coverage.
• [ ] Checked and updated guidelines.md which used to describe how to build, deploy and use DouTok.