move icons to folders and add PNG icons for Windows builds
moved icons to respective folders
added PNGs for ecm_add_app_icon() call. It doesn't work with a single SVG.
supplied various sizes according to the call in ecm_add_app_icon() here.
also, referred to cuttlefish for different icons at different sizes:-
NOTE: I did not use the PlaMo-like icon for the >=32px sizes. Instead I used the existing sc-apps-kdeconnect.svg.
I have tested the files to go exactly where they used to go earlier. So AFAIU this should not break anything.