Physical Dimensions Service in IIIF3?

[jbaiter]

trafficstars

Currently the IIIFv3 specification makes no mention of the "Physical Dimensions Service" that was introduced in IIIFv2.

Most importantly it's missing a type entry in the table in section "3.3.1 External Links", so it's currently unclear how to properly reference such a service from a v3 manifest.

See also this discussion in the IIIF Slack where @stephenwf shared some ideas on how it could be referenced from a v3 manifest: https://iiif.slack.com/archives/C18FHBKAQ/p1651228293150619

[tomcrane]

Will be done in P4 - see #2281