Upgrade away from Angular.js to Modern Angular

Disclaimer: Understand the difficulty of the task ahead. This is a long term goal.

Angular.js is incredibly out of date, and ideally we should use a much more modern framework. I am a fan of keeping this project as angular, because even though React is the hot new things, Angular still exists in industry and learning/using something different is a good thing.

As a part of this upgrade, we basically have to rewrite almost the entire frontend code, so this project will require a effective feature freeze until completion once begun.

I will start with using this guide: https://angular.io/guide/upgrade

It may be possible to have a hybrid angular.js and angular app, which could aid in the upgrade process.

The goal is to get up to Angular 9

从 issue 中链接的 Angular 升级指南开始，检查现有 frontend，以梳理需要重写的 Angular.js 代码。评估 Angular.js 和 Angular 混合应用是否能够支持渐进式迁移。完成意味着 frontend 已升级到 Angular 9，但 issue 没有定义中间里程碑或具体文件。

由索引模型根据 Issue 内容生成。