refactor(typings): 改善和纠正各种 id 类型的性质 #481
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各种 id 类型如：UserId, ProjectId, TaskId 等等，它们应该有下列性质：
1.可以赋给 string 类型（允许如：`const x: string = id as UserId`）
2.相互之间不可赋值（如遇 `const tid: TeamId = uid as UserId` 会报错，
需要手动强转）
3.string 不可以赋给它们（如遇 `const id: UserId = 'hello'` 会报错，需
要手动强转）
4.可以直接使用在对象 index 的位置
原来 `interface X extends String { kind?: 'X' }` 的实现，满足了2，但没
有满足1、3、4。
不满足1，导致当需要将 id 数据从带有场景上下文的业务代码传给不关心业务逻
辑而只是简单接受 string 的底层组件时，需要通过 `as string` 强转，如果
该信息包在一个对象结构里，那这个对象结构要么需要 `as any`，结果丢失所
有类型信息，要么底层组件的对应对象结构类型声明就需要添加类型参数（泛型
声明），结果增加冗长而意义不大的泛型声明。
不满足3，会漏掉很多类型检查，因为并不是任何 string 类型的值都可以赋
值给特定 id 类型的。
不满足4，有时通过把 id 作为 key，构建简易的字典对象时，就不得不麻烦地
在 [] 里写 `as string`。
新的写法是：
`type X = string & { kind: 'X' }`
它能同时满足1、2、3、4。
参考：
- https://codemix.com/opaque-types-in-javascript/
- microsoft/TypeScript#15807
- microsoft/TypeScript#4895
- microsoft/TypeScript#202
- https://github.com/Microsoft/TypeScript/blob/d9b93903c035e48c8da1d731332787f83efc4619/src/compiler/types.ts#L54
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各种 id 类型如：UserId, ProjectId, TaskId 等等，它们应该有下列性质：
const x: string = id as UserId）const tid: TeamId = uid as UserId会报错，需要手动强转）const id: UserId = 'hello'会报错，需要手动强转）原来
interface X extends String { kind?: 'X' }的实现，满足了2，但没有满足1、3。不满足1，导致当需要将 id 数据从带有场景上下文的业务代码传给不关心业务逻辑而只是简单接受 string 的底层组件时，需要通过
as string强转，如果该信息包在一个对象结构里，那这个对象结构要么需要as any，结果丢失所有类型信息，要么底层组件的对应对象结构类型声明就需要添加类型参数（泛型声明），结果增加冗长而意义不大的泛型声明。而不满足3，会漏掉很多类型检查，因为并不是任何 string 类型的值都可以赋值给特定 id 类型的。
新的写法是：
type X = string & { kind: 'X' }，它能同时满足1、2、3、4，并在类型报错信息里有比较友好的信息提示。TODOs:
参考：