Add support for chained / next actions
Summary:
This adds support for multiple actions following each
other through the "Next" value of Action dictionaries.
Test Plan: Activates the corresponding part of the visibilitytest.
Reviewers: Okular
Subscribers: sander, aacid
Tags: Okular
Maniphest Tasks: T8278
Differential Revision: https://phabricator.kde.org/D11609