Karbon image filter: Add multipage support
Summary: Adds ability to select page in the options dialog
Test Plan: Export to png and jpeg from page > 1.
Reviewers: anthonyfieroni
Reviewed By: anthonyfieroni
Subscribers: Calligra-Devel-list
Tags: #calligra:_3.0
Differential Revision: https://phabricator.kde.org/D25214