Valkyrize collection feature spec

[dlpierce]

Summary

Convert collection feature spec to valkyrie resources, add sorting spec; ref #6408

Guidance for testing, such as acceptance criteria or new user interface behaviors:

• Collection json response is correct; id is id: 'abc123', not a hash like id: { id: 'abc123' }

Changes proposed in this pull request:

• Use hyrax/base/show jbuilder partial for collection json response format.

@samvera/hyrax-code-reviewers