[PROTOTYPE] Implements chunked rendering

This PR implements chunked rendering of the operator list of each page. That is, we will render chunks of the operator list as they are parsed, rather than rendering after the  entire operator list has been parsed.

Before #2719, these changes had a significant improvement on the rendering times of PDFs with large operator lists such as the maps in #2541 and #2813. However, rebasing on the progressive loading changes of #2719 seems to have killed most of this improvement. I'll need to investigate if it's possible to gain back the potential improvements from chunked rendering.