`userButtonBox` is now a child of `userButtonTrigger`

The parent-child relationship of the two elements userButtonTrigger and userButtonBox has been swapped. Previously, userButtonTrigger was nested inside of userButtonBox, and now userButtonBox is nested inside of userButtonTrigger. This change resolves some usability issues in <UserButton />. If you are applying style customization to either of these elements, your customizations may need to be adjusted.