Toolbar state was not being saved / restored

Summary:
Create a new entry in the KCofig to save / restore
the ToolBars of the toolviews

Signed-off-by: Tomaz Canabrava <tcanabrava@kde.org>

Test Plan: manual testing

Reviewers: kfunk, apol

Subscribers: kdevelop-devel

Differential Revision: https://phabricator.kde.org/D4122

(cherry picked from commit b22bf9b4)