wallpapers/image: resize svg wallpaper to requested size
QImage is rasterized, which means it needs a defined size. If we need to resize a svg image, the svg image should be loaded by QSvgRenderer and then QPainter class is used to draw the image onto a new QImage with the desired size.
Plasma::Svg can help wrap the whole process and provide a cached image if the wallpaper is loaded again.
BUG: 469294 FIXED-IN: 5.27.6
(cherry picked from commit a3d0491d)
Edited by Fushan Wen