Feature/rosie the riveter collection

@barnabyalter, @jgpawletko this pull request implements the Rosie the Riveter collection which finishes user story #78290270

Highlights
- Define `NyucoreMetadata::Vocabulary`, with spec
- Define `Ichabod::Vocabulary`, which includes the term `resource_set`, with specs
- Define `Ichabod::NyucoreDatastream` with specs
- Clean up field constants on `Nyucore`
- Add `resource_set` "before load" of an Nyucore record from a ResourceSet, with specs
- Add "The Real Rosie the Riveter" `Collection` matcher, with specs
- Re-records all cucumber cassettes with the `resource_set` attribute
- Remove unused objects (`NyucoreMetadata`, `DublinCoreAsset`, `NyucoreRdfMetadata`)
- Change the instance method name from `ResourceSet::Base#create` to `ResourceSet::Base#load` since it doesn't necessarily create the Nyucore objects.

[Finishes #78290270]