Introducing where clause for number_of_works()

Based on some investigation around #3478, I suspect that the
`Hyrax::WorkRelation#where` call that uses only a depositor field and
user key is finding more results than the query run on the catalog
search page.

By adding the where clause, I hope to align the query logic of the
`number_of_works` and the `link_to_field` on the [_vitals.html.erb][1] partial.

Related to #3478

[1]: https://github.com/samvera/hyrax/blob/b04c41d2772505d8a548c3fd48774a5642d3ac90/app/views/hyrax/users/_vitals.html.erb#L11-L12

app/helpers/hyrax/dashboard_helper_behavior.rb

@@ -5,8 +5,9 @@ def on_the_dashboard?
       params[:controller].match(%r{^hyrax/dashboard|hyrax/my})
     end
 
-    def number_of_works(user = current_user)
-      Hyrax::WorkRelation.new.where(DepositSearchBuilder.depositor_field => user.user_key).count
+    def number_of_works(user = current_user, where: {})
+      where_clause = where.merge(DepositSearchBuilder.depositor_field => user.user_key)
+      Hyrax::WorkRelation.new.where(where_clause).count
     rescue RSolr::Error::ConnectionRefused
       'n/a'
     end

spec/helpers/hyrax/dashboard_helper_behavior_spec.rb

@@ -29,6 +29,12 @@
     it "finds 3 works" do
       expect(helper.number_of_works(user1)).to eq(3)
     end
+
+    context "with a :where clause" do
+      it "limits to those matching the where clause" do
+        expect(helper.number_of_works(user1, where: { "generic_type_sim" => "Big Work" })).to eq(1)
+      end
+    end
   end
 
   describe "#number_of_files" do
@@ -61,11 +67,13 @@ def create_models(model, user1, user2)
     solr_service = Hyrax::SolrService
 
     # deposited by the first user
-    3.times do |t|
+    2.times do |t|
       solr_service.add id: "199#{t}", "depositor_tesim" => user1.user_key, "has_model_ssim" => [model],
-                       "depositor_ssim" => user1.user_key
+                       "depositor_ssim" => user1.user_key, "generic_type_sim" => "Work"
     end
 
+    solr_service.add id: "1993", "depositor_tesim" => user1.user_key, "generic_type_sim" => "Big Work", "has_model_ssim" => [model], "depositor_ssim" => user1.user_key
+
     # deposited by the second user, but editable by the first
     solr_service.add id: "1994", "depositor_tesim" => user2.user_key, "has_model_ssim" => [model],
                      "depositor_ssim" => user2.user_key, "edit_access_person_ssim" => user1.user_key