For VCS-plugin interface added pure virtual function outOfVersionControlActions()

Summary: This commit changes VCS-plugin interface in order to provide actions for unversioned items (for example clone or checkout repository), updates to dolphin-plugins comes in the separate commit D29042.

Reviewers: Dolphin, meven, elvisangelaccio

Reviewed By: Dolphin, meven, elvisangelaccio

Subscribers: kfm-devel

Tags: Dolphin

Differential Revision: https://phabricator.kde.org/D29041