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

まだ誰も着手していません。

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.

まず、`@param` と `@return` のアノテーションを挿入する、`---` によってトリガーされる既存の候補を追跡し、次に言語サーバーでコードアクションが公開されている箇所を調べます。同じアノテーションの挿入がコードアクションから利用でき、関数ヘッドで引き続き見つけられれば完了です。

索引モデルが issue の本文から書いたものです。