Allow OSD (IIIF Manifest driven) to fallback to a static image if no IIIF Service (info.json) is provided

[DiegoPino]

What?

If a IIIF manifest canvas/image (e.g an external static source) has no Service definition, my new IIIF code parsing JS assigns a missing ID (undefined/info.json) and thus fails to load the image.

I mean, having an info.json so OSD can property tile is desired but there are many cases where that won't be possible and this needs to be fixed by defaulting to the parent "id" value instead of a non existing service id

This is a bug and it is my fault 😞

[DiegoPino]

Needs to be revisited