【Feature request】- outline of code (at least common used types like markdown, c/c++, python, etc)

[Giessen]

[Feature request description] A sideabar showing the headlines/structure of current code/text file.

[Why] When browsing through a long text file (e.g., markdown type), it's painful to locate and navigate. An outline of contents at sidebar would greatly improve the efficiency.

[Reference] https://github.com/hedyhli/outline.nvim?tab=readme-ov-file

[Appearing like this]

Thank you very much for the great work.