WIP: Allow playback of "plain" Rich Media
Okular currently only supports Flash based Rich Media by a compatibility layer. Flash is no longer relevant, but the compatibility layer still is -- for old documents. New documents however, have no reason to depend on Flash and maybe will use the Flash-free Rich Media annotations. They are very plain -- no control using actions, no controls, etc. This means that this MR essentially brings full support of plain Rich Media.
This MR depends on https://gitlab.freedesktop.org/poppler/poppler/-/merge_requests/855.
Edited by Michal Vlasák