Split QSvgWidget out ot QtSvg to remove dependency on Widgets

The Qt SVG module has a dependency on Qt Widgets due to it having a QSvgWidget.
This is quite inconvenient when writing a pure QtQuick-based mobile application since there QtWidgets increases the package size by almost 3MiB which is roughly 20% the package size.

Given there is a Multimedia Widgets module separate of Multimedia and the same for Webkit, the QSvgWidget should be split out of QtSvg to reduce overhead when using Svgs in the aforementioned application since SVGs ease the creation of scalable, crisp user interfaces.