Properties (getter/setter) support

還沒有人認領這個 Issue。

Lua's variables can act as C#-like properties by setting `__newindex` appropriately.

Getters and setters occasionally have different type signatures. However, the `@field` annotation can only represent one type.

```lua
-- hoge.meta.lua

---@meta

---@class Point
---@field x number
---@field y number
Point = {}

---@class Hoge
---@field position Point ⚠️ actually a property
Hoge = {}

---@return Hoge
function new_hoge() end
```

```lua
-- main.lua

local hoge = new_hoge()
hoge.position = { 3, 7 } -- emits "Missing required fields in type `Point`: `x`, `y`"
print(hoge.position.x) -- 3.0
print(hoge.position.y) -- 7.0
```

(Full sample program is [here](https://codeberg.org/haruomaki/luaproperty))

It should be annotated as "`position`'s setter receives a `table`, and its getter returns a `Point`."

How about adding a new syntax to describe this?

先從 hoge.meta.lua 和 main.lua 中的註解範例開始，然後重現將一個表格指派給 hoge.position 時的診斷。該 issue 未指定任何儲存庫檔案或測試，因此必須找到相關的註解和型別檢查進入點。完成的標準是：註解語法可以表達不同的 setter 和 getter 型別，而且範例指派不再回報缺少 Point 欄位。

由索引模型根據 Issue 內容生成。