Contains also:

tdf#106867: Implement pptx export of AnimationNodeType::COMMAND.
tdf#106867: Import target for commands in PPTX.
tdf#106867: Write also the extended markup to fully support embedded videos.
tdf#106867: Unit test for the export of embedded videos.

Change-Id: I7f4f389a72aa7ecef65d87f07bb69ba8f3374a14
Reviewed-on: https://gerrit.libreoffice.org/42017Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>