Refactor subject pages to have re-usable macros

[jimchamp]

Closes #9785

Extracts three subject page components into macros:

• ProlificAuthors.html: The list of prolific authors on a subject
• PublishingHistory.html: The publishing history graph for a subject
• RelatedSubjects.html: Links to related subject pages

Additionally, removes unreferenced renderPublishers jsdef function.

The existing carousel is a custom_carousel template, and hasn't modified.

Technical

renderSubjects in the RelatedSubjects macro is no longer a jsdef function. This function worked properly when called from the browser console, but wasn't referenced in our codebase.

The renderAuthors jsdef function was not included in the ProlificAuthors macro. This function did not work properly when called from the console, due to an Uncaught ReferenceError: page is not defined error. Also, it isn't referenced in our codebase.

Testing

1. Before deploying these changes, navigate to a subject page.
2. Open another tab.
3. Deploy the branch.
4. Open the same subject page in your new tab. Content, styling, and functionality should be the same when the tabs are compared.

Screenshot

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