QmlDesignerr: Auto detect presence of QtQuick.Timelnie module

The Timeline editor in the QmlDeigner plugin depends on the QtQuick.Timeline module being available to the qmlpuppet.

Since this module was not installed by default until Qt 5.14, we had a checkbox in the settings which was by default off. Now, with 5.14, that setting will be by default on.

However, a smarter way than such a checkbox would be an auto-detection in the QmlDesigner plugin whether it can offer the Timeline editor or not. Suggested here: https://codereview.qt-project.org/c/qt-creator/qt-creator/+/286777