EPUBExportUIComponent::execute() still needs to launch an actual dialog,
but otherwise it has enough functionality that only tweaking
maFilterData is necessary in the UNO component to pass custom filter
options to the exporter.

Change-Id: I95af024f5babd66a5aa0b446550f4f0fec45ef43
Reviewed-on: https://gerrit.libreoffice.org/42204Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>