Add ability to select overlapping shapes in `ui.image_annotator`

#### Is your feature request related to a problem? Please describe

Currently, it is not possibly to select overlapping shapes in the `ui.image_annotator` component.
One will need to move away or to delete the topmost shape first to be able to select the shape below. (see video below)

#### Describe the solution you'd like

One solution would be to implement a looping functionality, where for each click on a stack of shapes, the next layer will be selected.

#### Describe alternatives you've considered

An annotator could always start with the largest box. When a smaller box is drawn onto a bigger box, both are still selectable.

#### Additional context

https://user-images.githubusercontent.com/1069138/205308127-7557ba53-624c-422d-9cf7-087e0ac93aaf.mp4

Start by locating the implementation and interaction entry points for the `ui.image_annotator` component, then reproduce the overlapping-shape case shown in the linked video. The change is done when clicking a stack of shapes allows each underlying shape to be selected without moving or deleting the topmost shape.

Written by the indexing model from the issue text.