Support Wayland rectangular selection HiDpi
When the drawn rectangle is on a single screen, the output image uses the screen native resolution. When the drawn rectangle is on screens with multiple scale factor, the output image is upscaled to correspond to the screen with the hightest scale factor as to keep the image not distorted.
Full screen screenshots are now in native size by default. Adds also a "scaled" full screen mode, to capture screens content downscaled to screens virtualsize allowing for not distorted content.
There is a small fix concerning positioning of help text.
Kwown issue : with multiple screens and multiple scale factor, during the region selection the screens with a scaling factor will appear blurry, this does not affect the end result though.
Requires Plasma 5.19.80+
BUG: 409762 BUG: 420863 FIXED-IN: 20.12