about dialog: Fix the logo in a multiplatform way

The Icon was renamed in #8283 for Linux builds, and the fix proposed in #8312 would in turn break
the icon for Windows users.

I've decided to fix the aboutdialog.ui file via qtcreator.

I'm not sure its important to have the yuzu icon inside the About dialog grabbed from the local Qt theme,
but I've reword how the code works for that, and we can just delete those lines.

I've also thrown the yuzu.png through pngcrush to remove this warning
libpng warning: iCCP: known incorrect sRGB profile

Credit to abouvier for bringing bug up.