Create bf:PaginationFoliation as a subclass of bf:Extent

[sfolsom]

Justification: The Sample Data section in https://github.com/LD4P/arm/blob/master/modeling_recommendations/pagination_foliation.md provides numerous pagination and foliation examples that provide fuller details of the extent, which currently cannot be accommodated fully by bf:extent/Extent, bf:unit/Unit, bf:count. The pagination and foliation requires understanding the sequence of various counts of pages, foliation, etc., and while one option is to turn each count into a bf:Unit, there is currently no way to order the various bf:Units and unlikely that it would be sustainable to maintain these a separate resources.

If not using separate bf:Unit resources to capture information (and rather than introducing a new datatype property for pagination and foliation), creating :PaginationFoliation as a subclass of bf:Extent allows the property query path to remain the same as the more general bf:Extent pattern, while still saying this particular extent is speaking specifically to the pagination and foliation of a bibliographic resource.

[This recommendation was made on behalf of the LD4P Art & Rare Materials BIBFRAME Ontology Extension (https://github.com/LD4P/arm).]

[kefo]

The presence of this class in ARM has made this status of this request unclear.

https://github.com/Art-and-Rare-Materials-BF-Ext/arm/blob/main/v1.0/ontology/arm_1_0.rdf

[jak473]

We'd deprecate arm:PaginationFoliation if created in BF