Override spam checks when adding or editing books

[jimchamp]

Closes #6363

Spam checks for adding new books and editing works and editions are now skipped if the request was submitted by an admin or librarian.

Spam checks for creating new lists and updating patron profiles have not been affected.

Technical

New boolean parameter allow_privileged_edits has been added to is_spam(). If ever we want to bypass list and profile spam checks, we need only add the parameter to those is_spam() calls.

Testing

Test BAU functionality:

1. Log in as a non-privileged patron.
2. Attempt to add a book that contains a spam word in it's title. Expect this to fail.
3. Navigate to a book page and click the edit button. Attempt to add a spam word to any edition field and submit the form. This should fail.
4. Repeat step three, but add a spam word to a work field instead. Expect this to fail.

Test new functionality:

1. Log in as an admin or librarian.
2. Repeat steps 2 through 4 in the "Test BAU functionality" section, above. Expect each step to succeed, and ensure that they do.
3. Don't forget to delete the new book (if it is not real), and revert all edits (if they were not real edits).

Screenshot

Stakeholders

[mekarpeles]

perfect, thank you