Add IIIF manifest logo link to record page

[jrdh]

A IIIF manifest can now be generated for each record by going to https://data.nhm.ac.uk/iiif/resource/<resource_id>/record/<record_id> (e.g. https://data.nhm.ac.uk/iiif/resource/8d76e3e4-bcef-48f3-a32c-b72e2b8b300b/record/1955) (assuming the resource is configured correctly). It'd be nice to show the IIIF logo with a link to this manifest on each record page where it's appropriate to do so.

Couple of notes:

• it'd be good to have a reliable way to determine if a manifest can be generated or not (maybe an action in ckanext-iiif?)
• in fact it would probably be sensible to have an action in ckanext-iiif for manifest generation based on certain parameters. ckanext-iiif is currently setup in a way that allows other extensions to define routes under /iiif/ through an interface. Each route can then build a manifest. The intention behind this was to allow arbitrary manifest creation, e.g. we could have /iiif/search/<slug> which creates a manifest for a search result. Currently only /iiif/resource/<resource_id>/record/<record_id> is defined. This could totes be changed though!

[jrdh]

• Use actions for IIIF resource generation and refactor most of the codebase ckanext-iiif#7
• Add iiif manifest link to records #604