Add METS / IIIF Data to ChildObjects in Manifests

[maxkadel]

Add label and viewing hint to Canvases (child object level) in manifests

• [x] Label
• [x] "viewingHint" https://iiif.io/api/presentation/2.1/#viewinghint

(These were already being recorded, the others aren't needed on the manifests, only work done on this ticket was verifying)

[maxkadel]

Get from METS and save to DB for child objects (different ticket)

• [ ] Physical order
• [ ] Label
• [ ] Caption (non-LB only) (done for LB)
• [ ] "viewingHint" https://iiif.io/api/presentation/2.1/#viewinghint ?