Add holds by source report

[jazairi]

Why these changes are being introduced:

We need to be able to see the holds for a given degree period,
filtered by hold source.

Relevant ticket(s):

https://mitlibraries.atlassian.net/browse/ETD-462

How this addresses that need:

This adds a report of holds that allows filtering on thesis
grad date and hold source.

Side effects of this change:

• Report#extract_terms now checks for the type of items in the
  collection, so as to accommodate non-thesis collections.

Developer

• All new ENV is documented in README
• All new ENV has been added to Heroku Pipeline, Staging and Prod
• ANDI or Wave has been run in accordance to
  our guide and
  all issues introduced by these changes have been resolved or opened as new
  issues (link to those issues in the Pull Request details above)
• Stakeholder approval has been confirmed (or is not needed)

Code Reviewer

• The commit message is clear and follows our guidelines
  (not just this pull request message)
• There are appropriate tests covering any new functionality
• The documentation has been updated or is unnecessary
• The changes have been verified
• New dependencies are appropriate or there were no changes

Requires database migrations?

NO

Includes new or updated dependencies?

NO

[coveralls]

Coverage increased (+0.03%) to 97.123% when pulling 99b7508 on etd-462-holds-by-source into 85b0186 on main.

[jazairi]

It occurred to me a little late in writing this report that it might actually belong in the Hold model and controller instead of Report, since it doesn't use many of the Report features. I'm ambivalent as to whether it's worth a refactor, but I wanted to put that on the radar of whoever reviews this.

[JPrevost]

There are some N+1 queries in this report. See note in other PR for how to detect and please let me know if you'd like to pair or further discuss how to resolve.

Additionally, as a non-blocking comment it's a bit odd that the link to the Thesis from the Hold list goes to an Edit view and not either the Thesis#show or Hold#show. Is this hard coded in the Report framework? (I tried to figure out how the links got generated and gave up).

[jazairi]

@JPrevost We'd initially linked to the show view in reports, but stakeholders requested the edit view instead. More info here: db49c1c

I'll look into fixing the N+1 queries shortly. Thanks!