Allow downscaling shaders

[pyrareae]

It would be size to render the shaders at a lower resolution than the screen size. In my case for example I am using a 4k monitor with a fairly modest gpu, so a lot of the more intensive shaders stutter.

[y4my4my4m]

@lunarfyre7 yes, ive considered this at the moment i'm refactoring the whole code and splitting the settings/customizations into separate windows.

In the meantime you could probably achieve the result you want by modifying: ~/.local/share/plasma/wallpapers/online.knowmad.shaderwallpaper/contents/ui/Components/ShaderEngine.qml

Around the startCode and/or vertexShader parts and maybe defaultResolution.