Suggestion: Make `@param;@return` available as code action

還沒有人認領這個 Issue。

One really nice feature of the lua-lsp is that by typing `---` above a function, we get the `@param;@return` suggestions which auto-inserts function annotation.

Would it be possible to make this feature available via code action as well? Right now, it takes a bit of repetitive work to get the annotations inserted. When at the function head: `up`, `-`. `-`, `-`, `enter`. By using a code action, this could be reduced to one hotkey (and depending on your editor, maybe one extra `enter`).

Another benefit would be that making this available as code action would increase the discoverability of this feature. For a while, I didn't know that this very useful feature even existed. By being a code action, it would be far easier to discover for new users.

首先追蹤由 `---` 觸發、用來插入 `@param` 和 `@return` 註解的現有建議，然後檢查 language server 在哪裡提供程式碼動作。完成的標準是：可以透過程式碼動作執行相同的註解插入，並且在函式標頭處仍然可以發現這項功能。

由索引模型根據 Issue 內容生成。