Add option to disable most animations (reduce motion)

[bjorn3]

For example when clicking on a reply to a post, it currently slides in a new page from the right side and at the same time on this new page slides the post down from the top to right below the post it was replying to. This is rather distracting to me. A reduce motion option would make the new page to instantly cover the screen and ideally ensure that the post is already at the final location right below the post it replies to when showing the new page without any animation.