Fix meson installing wrong cursors and other cleanup
It looks like a change I made for testing snuck in to my last MR, the logic was backwards so that the .cur files are being installed only when not in Windows instead of in Windows.
This MR also includes fixes based on feedback from @xclaesse:
- Cleanup the tags used, remove the license and index tags, add the runtime tag to installed data
- Use an adwaita_dir variable to reduce repeating getting the datadir so many times