Adds an X button next to share and bookmark buttons on X.com posts to quickly click "Not interested in this post"

Prompt: The button works great in general, but it is a bit messed up when viewing a full post (e.g. on the status page vs home page). Fix the positioning of the x here, but do not impact it in other places (e.g. the x on replies and posts on the home page are fine and should not be changed).