Add support for previewing a IIIF manifest reference

[thatbudakguy]

There's a couple of things to consider here.

Unlike #69, we might have paged content with multiple canvases in this case. Now we would be getting into functionality that existing IIIF viewers definitely can handle better.

The path to rendering this could look very different depending on whether the source includes IIIF georeference annotations.

• If we don't have georeference annotations, we might want to use OpenSeaDragon's simple built-in collection paging tools.
• If we do have georeference annotations, we're in business: we can use the AllMaps MapLibre plugin to warp and render everything right onto our map. This is the ideal case! It would be super cool to support this natively in this viewer.

[thatbudakguy]

See related geoblacklight/geoblacklight#1625

[thatbudakguy]

OpenSeaDragon has a basic "sequence mode" with thumbnail filmstrip, so we could potentially use it for both image content and manifest content if there's not enough info to place the image on a map.