feat: allow the placement co-ordinates to be copied with a click

Allow these to be copied and pasted with a click, the way it is for color.

Helps to place the same item on the next slide while creating animations

No file or test is named. Start at the placement coordinate controls shown in the issue and trace the existing click-to-copy behavior for color; done means the coordinates can be copied and pasted with a click for reuse on another slide.

Written by the indexing model from the issue text.