Solving problem with icons using software rendering

I'm from Brazil and here we have a lot of obsolete equipment that needs to use software rendering, the two main problems were with the desktop icons that don't show shadows, so using a rectangle as it was used until kde 5.5 improves the result.

I'm submitting again, as I had difficulty resolving git-related issues

Also included is the change to the icons on the taskbar that when using overlay do not appear using software rendering.