windows: add copy of Kate icon for unplating
https://docs.microsoft.com/en-us/windows/msix/desktop/desktop-to-uwp-manual-conversion#optional-add-target-based-unplated-assets and https://github.com/MicrosoftDocs/windows-uwp/issues/1827 suggest adding a copy of the logo to the same folder to achieve unplating in the start menu and other places.
Closes #54
Draft because: untested, no idea whether this works
Optimally, someone with a Windows toolchain would give this a quick try