Support Mirror shape
A mirror shape draws a graphic that is an exact mirror image of a specific subject. For example, you can use the mirror if the same frame needs to appear on multiple pages and any changes to the frame should apply to all of them.

- [x] Add `Mirror` shape (has `subject` property)
- [x] Draw mirrored shape based on `subject` reference.
- [x] Allow to manipulate the scale of mirror with a controller