Square brackets ignore class field check

還沒有人認領這個 Issue。

### How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

### Which OS are you using?

Linux

### What is the issue affecting?

Type Checking, Diagnostics/Syntax Checking

### Expected Behaviour

Classes check fields correctness regardless of access form class["bad"] and class.bad should both cause error

### Actual Behaviour


### Reproduction steps

Create class with fields. Access to non-existing field using `["field-name"]`.

### Additional Notes

_No response_

### Log File

_No response_

在 Lua language server 中，使用寫成 class["field-name"] 的類別欄位存取來重現診斷，然後將其與 class.field 進行比較。追蹤負責類別欄位查找的型別檢查與診斷路徑；完成的標準是兩種存取形式都一致地回報不存在的欄位。

由索引模型根據 Issue 內容生成。