Add Bulk Checker module to Detector::Journal

** Why are these changes being introduced:

Now that the Detector::Journal model is only concerns with detections,
and calling Detector::Journal.new no longer spawns any database records,
we can implement the BulkChecker module for better developer experience.

** Relevant ticket(s):

* https://mitlibraries.atlassian.net/browse/tco-110

** How does this address that need:

This defines a @Detections attribute on the Detector::Journal class,
as well as an initialize method to populate that attribute based on the
full_term_match method.

This allows the BulkChecker-provided .check_all_matches method to return
meaningful information.

** Document any side effects to this change:

This implementation may be too minimal, as the initialize method ends
up calling the singleton methods in a slightly awkward way (or maybe I
need to get used to this way of working, and not expect to just call
full_term_matches directly in the initializer).

app/models/detector/journal.rb

@@ -14,6 +14,15 @@ class Detector
   # Detector::Journal stores information about academic journals loaded from external sources to allow us to check our
   # incoming Terms against these information
   class Journal
+    attr_reader :detections
+
+    # shared singleton methods
+    extend Detector::BulkChecker
+
+    def initialize(phrase)
+      @detections = Detector::Journal.full_term_match(phrase)
+    end
+
     # Identify journals in which the incoming phrase matches a Journal.name exactly
     #
     # @note We always store the Journal.name downcased, so we should also always downcase the phrase

test/models/detector/bulk_checker_test.rb

@@ -11,7 +11,9 @@ class CitationTest < ActiveSupport::TestCase
     end
 
     test 'journal_bulk_checker' do
-      skip 'Detector::Journal does not yet support bulk_checker'
+      bulk = Detector::Journal.check_all_matches(output: true)
+
+      assert_equal(1, bulk.count)
     end
 
     test 'lcsh_bulk_checker' do