Comet: Update to Hyrax 5.2

The next release of Hyrax 5.2 should be Rails 6 compatible, which would make this an easier lift than we thought it was going to be.

Overrides / hacks to remove:

• spec/support/workflow - use hyrax:workflow:load task again instead of loading workflows by hand (leverages hyrax#7043)
• comet/lib/comet/characterization_service.rb (possibly modified by #1867 (closed)) - use code from hyrax#7088 instead of rolling our own apply_metadata method