Add `provider` and add properties

[mathewjordan]

Hey Stephen,

Currently it seems the best way to add provider is to append after a resource is built and converted to 3.0.

The nature of provider https://iiif.io/api/presentation/3.0/#provider is interesting. Should both Collections, Manifests, and Canvases be able to have an addProvider function? Understanding the structure of provider is a bit heavy with label, homepage, logo, and seeAlso, this might be less than easy.

Best,
Mat

[adamjarling]

@stephenwf Same here, we're up for helping out with this issue and have it planned into our work Northwestern cycle.

[stephenwf]

A dedicated provider helper sounds very useful. I think the provider can be on any resource, so would fit nicely into the BaseEntityBuilder I think.

[stephenwf]

@adamjarling @mathewjordan I've added some extra documentation to the README for how the builders work internally
https://github.com/stephenwf/iiif-builder/blob/main/README.md#baseentitybuilder

If there is anything unclear, please let me know!