Allow greater values in unit_offset

Created by: KoBeWi

Turns out I was wrong in https://github.com/godotengine/godot/issues/35485#issuecomment-577871079, the hints are just defined in few places.

Previously inspector accepted only unit_offset lesser than 0, now you can put values greater than 1 too. They will of course be manually clamped/wrapped, but this does not happen in animations, so you can input any value there.

This should resolve #35485 (closed) @avencherus