[Feature request]: Cast class fields

If I have any class, and I get a warning like the following on a function that is being given a class field as a parameter (e.g., tohex(class_name.class_field)):

Cannot assign `string|integer` to parameter `integer`.
[Lua Diagnostics.: param-type-mismatch]

Is there already a way to cast this class field? If not, could it be implemented?

When trying to cast something like ---@cast group.foreground -string, I get the warning:

Unknown type conversion variable `{}`.
[Lua Diagnostics.: unknown-cast-variable]

首先跟踪 issue 中描述的 unknown-cast-variable 和 param-type-mismatch 诊断，然后检查 cast 当前如何解析变量和类字段。当诸如 ---@cast group.foreground -string 这样的 cast 被接受，并且在将该字段传递给仅接受整数的函数时移除报告的类型警告，即表示完成。