(Ozone) Fix blurry sidebar icons
Created by: jdgleaver
As described in this issue: https://github.com/libretro/RetroArch/issues/10363, the system tab icons shown in Ozone's sidebar (and to a lesser extent, the top left RetroArch icon) are very blurry at high scales and on large high resolution displays - for example:
This PR increases the resolution of the affected PNG images such that their visual appearance is consistent with the other menu icons (scaling has also been tweaked for greater uniformity):
Moreover, the system tab sidebar icons and main RetroArch icon are now generated via the export_ozone.sh
script, so they can be updated easily in the future.
This PR closes https://github.com/libretro/RetroArch/issues/10363