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

Nobody has claimed this yet.

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.

Start by tracing the existing `---`-triggered suggestions that insert `@param` and `@return` annotations, then inspect where code actions are exposed by the language server. Done means the same annotation insertion is available through a code action and remains discoverable at a function head.

Written by the indexing model from the issue text.