Fix translation of toolbar name when it has i18n context

Summary:
The Configure Toolbars dialog did not take into account the "context" attribute of toolbar text which should be used as i18n context string.

KDE Partition Manager was affected:

<ToolBar name="editToolBar">
  <text context="@title:menu turn on and off edit toolbar">Edit Toolbar</text>
[...]

Test Plan: Run partitionmanager and check translated toolbar names in: 1. Configure Toolbars dialog; 2. In the menu under "Tools -> Toolbars Shown".

Reviewers: dfaure, apol

Reviewed By: dfaure, apol

Subscribers: Frameworks

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D8767