Support for headers/footers in printToPdf

We currently use wkhtmltopdf's C++ library to convert HTML to a PDF. However it has various bugs, such as fonts being compressed horizontally and rendering too large.

I tested with

QWebEnginePage->printToPdf()

and it does not have these font issues; it renders correctly. However, Qt's printToPdf() does not support headers/footers, and it adds a "PAGE 2:" label at the top-left page 2 (and so on for each page), and there is no way to disable or customize this.

It would be a perfect solution for us if there were a way to specify custom headers/footers per page (I supply the HTML). Long-term we'd need to be able to have different headers/footers used depending on the pager number.

The way I see this working is I provide getHeader(short pageNum) and getFooter(short pageNum) callbacks to printToPdf() that return HTML for those headers/footers. I'd also need to be able to specify margins and how much of the page the header/footer takes up.