I10 replace indexes relationships with lv implementation

[ShanaLMoore]

Port over the following from Louisville. It should replace iiif_print's indexes_relationship.rb

• set_child_works.rake from lousiville

• port lib/rdf/custom_is_child_term.rb from Louisville

• port app/models/concerns/set_child_flag to a mixin, include in work types

• get app/indexers/hyrax/file_set_indexer and put it in a mixin, include in file_set_indexer

• get all_decendant-file_sets and ancestor_ids from app/indexers/app_index.rb and put it in an indexer mixin

• specs: Time boxed it - will create a ticket to revisit them later on. Currently I'm unable to test this in the UI but this otherwise is what LV has. ref: Clean up specs #43

• tested generator behaves as expected

• manually verified the relationships get formed

• child's is_child_bsi is set to true as seen in the solr dashboard. is_page_of_ssim is populated, which proves the ancestor method works.
  

• forms relationship w bulkrax importer

• sample file: iiif_print_test.zip
  

• catalog should only display parents

child view

• thumbnail does not render due to WIP. (newspaper page model has been removed) - to be handled in a separate ticket

• parent's manifest.json includes child's id (90f946ef-519e-42d7-ae7f-af77466143b1)

• able to run rake task
• verify generator looks OK (it may need changes later - i created a ticket to review this towards the end of the project when all the moving pieces settle)

[ShanaLMoore]

TODO - create a separate ticket to revisit the UV manifest. This one is taken from LV hyrax 2.9.6 so it'll prob need to be updated.

This is responsible for displaying the children in the uv and its metadata.

[kirkkwang]

Looking good!