[Feature Request] @mixin - @class specific syntax to define applied mixins

What

A way to indicate that the members of a @class type are applied to a subject @class outside of the inheritance chain

Technical

@mixin type, ...
Adds the values of type, ... to the subject class' definition. Mixins are applied in the order they are specified; values of the same key are overwrote as each mixin is processed

Example

This:

---@class Mixin1
---@field foo number
---@field bar number

---@class Mixin2
---@field bar string
---@field baz string

---@class Subject
---@field key boolean
---@field foo boolean
---@mixin Mixin1, Mixin2

Would get interpreted as

---@class Subject
---@field key boolean (defined by field; wasn't altered by mixins)
---@field foo number (defined by field, overwrote by mixin1, not overwrite by mixin2)
---@field bar string (defined by mixin1, overwrite by mixin2)
---@field baz string (defined by mixin2)

Use case

I currently have sub-classes that get assigned valves from reusable dictionary tables outside their inheritance chain. The only way to document those modifications is to statically define the fields each time a mixin is applied

未指定文件或测试。首先跟踪 language server 如何解析现有的 @class 注解和继承，然后确定有序应用 @mixin 和字段覆盖应适合放在哪里。完成的标准是：语法按照所述的优先级规则进行解析，并且有针对多个 mixin 和冲突的测试覆盖。