Feature request: Export PDF with comments

I suggest a feature to download the output PDF including the comments added through overleaf's UI. I believe that this could be achieved fairly easily, for example, by integrating with pdfcomment.sty. Here's an example of a PDF using pdfcomment.sty.

This is a copy/paste of an old request by filipefigcorreia that I think having that could be really usefull: https://github.com/overleaf/web/issues/747