Add contents hierarchy to collection display (ARC-149)

[ssciolla]

To Do

• Add Contents to sidebar navigation
• Add Aeonform functionality - see inventory of Aeon code in umich, especially aeonform.js https://mlit.atlassian.net/browse/ARC-161
• Fix navbar styling
• Investigate wrapping of Javascript (IIFE) (can we remove it?) Yes. With current modules method not necessary, but good to have for standalone js.
• Finalize JS loading pipeline
• Fix strong parameters?

  Unpermitted parameters: :contents, :key, :paginate. Context: { controller: CatalogController, action: hierarchy, request: #<ActionDispatch::Request:0x0000000126c232c0>, params: {"contents" => "true", "key" => "-document", "paginate" => "true", "controller" => "catalog", "action" => "hierarchy", "id" => "umich-bhl-032"} }
  

• Make interesting(?) items links (items are linked always right now, no counter is in use)
• Tidy up show more/ show less (truncation control shows even when it's not needed).
• Fix indentation

[rshiggin]

What changed and why

• jQuery removed entirely
• turbolinks:load → turbo:load. Turbolinks is gone in Rails 8.
• navigation.contains.elements → turbo:frame-load. In ArcLight 1.x, contents pagination arrives via turbo-frames, so turbo:frame-load is the correct replacement.
• Event delegation replaces per-element binding. The new model: one listener on document, forever, when you click a checkbox, the change event fires on the checkbox, then bubbles up through every ancestor: label → div → body → document. A listener anywhere on that path hears it.
• Event delegation instead of per-element binding. One change listener on document replaces BindEvents()/SelectCheckbox binding to each checkbox and the data-initialized guard. New checkboxes work automatically.
• CSS.escape() used when building the value selector in restoreCheckboxes, preventing breakage/injection from special characters in identifiers.
• harvestItemMetadata uses a dirty flag to save state only once (old buildCollectionItemsMap called saveCollectionItems() inside the loop on every item).
• Removed sessionSave utility and its null-removal branch; saving is now inline in saveState.
• Constants CHECKBOX_SELECTOR and FORM_ID replace repeated string literals.

Net effect: same behavior and storage format, but dependency-free, Turbo-compatible, more robust to dynamically loaded content, and safer/cleaner.