Expand target of Annotations to Support Content State Recipes

[markpbaggett]

This relates to this iiif-prezi3 issue.

In order for the content state recipes to be valid, it seems like the JSON schema needs to be modified. The recipes include:

• https://iiif.io/api/cookbook/recipe/0485-contentstate-canvas-region/
• https://iiif.io/api/cookbook/recipe/0540-link-for-opening-multiple-canvases/

The code in question appears to be this:

https://github.com/IIIF/presentation-validator/blob/main/schema/iiif_3_0.json#L957-L967

It seems like it should be something like this:

"target": {
    "anyOf": [
        { "$ref": "#/classes/annoTarget" },
        {
            "type": "array",
            "items": {
                "$ref": "#/classes/annoTarget"
            }
        },
        { "$ref": "#/classes/canvasRef" },
        {
            "type": "array",
            "items": {
                "$ref": "#/classes/canvasRef"
            }
        },
    ]
}

[glenrobson]

I think this would be better in the annotationTarget so it doesn't need to test the array and single:

presentation-validator/schema/iiif_3_0.json

Line 973 in 1aaaaee

"annoTarget": {