Fix rotated element display in InteractiveImage

Refs #938 (closed)

The bounding box used to set the viewBox on the global SVG element was using the boundingBox helper, which restricts to the dimensions of the image (which is the most common use case, since this is mostly used for IIIF URLs). But with rotation, it is perfectly possible to get polygons that go out of the original image's bounds.

More work is required in other places on the InteractiveImage to allow annotation to work properly, since rotating to 90 or 270° can cause "invisible walls" to show up when editing: drawing a polygon near the sides is not possible.