Updates in response to KVersionControlPlugin interface changes.

Authored by nikolaik on Apr 30 2020, 1:56 PM.

Description

Updates in response to KVersionControlPlugin interface changes.

Summary:
Updates VCS-plugins for the new KVersionControlPlugin interface. Updates available in the separate commit D29041.
Plugins unversionedActions() functions now do nothing so it doesn't change any current plugin behaviour.

Reviewers: Dolphin, meven, elvisangelaccio

Reviewed By: Dolphin, meven, elvisangelaccio

Differential Revision: https://phabricator.kde.org/D29042