[glib] Expose more fields from MediaRendition in PopplerMedia
I'm using pdfpc for presentations. It supports playing embedded movies, but not autoplaying them, because the auto-play parameter isn't exposed in the glib API.
I'm not 100% sure that I did the right thing here, since pdfpc is built using Vala and that means I need to regenerate the Vala bindings as well, which I haven't figured out how to do yet.
CC @fnevgeny