show 'annotate' icon when submitted but not graded

closes EVAL-1590
flag=annotated_document_submissions

Test Plan:
1. Create a "student annotation" assignment.
2. As a student, before submitting go to the student grades page and
   notice that the 'Score' column for the assignment shows '—'.
3. As the student, submit to the assignment.
4. As the student, go to the grades page for the course. Notice that
   the 'Score' column for the assignment shows an 'annotate' icon (a
   piece of paper with a pencil).
5. As the teacher, grade the student in SpeedGrader.
6. As the student, go the student grades page. Verify the icon is no
   longer there and the score has taken its place.

Change-Id: Ifeb554e5fce73ff201b6b04f48d56ada5f41401d
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/263023
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Eduardo Escobar <eduardo.escobar@instructure.com>
Reviewed-by: Adrian Packel <apackel@instructure.com>
QA-Review: Spencer Olson <solson@instructure.com>
Product-Review: Jody Sailor

app/helpers/gradebooks_helper.rb

@@ -69,6 +69,11 @@ module GradebooksHelper
         :icon_class => 'icon-filmstrip',
         :screenreader_text => I18n.t('icons.media_submission', 'Media Submission')
       }
+    when 'student_annotation'
+      {
+        icon_class: 'icon-annotate',
+        screenreader_text: I18n.t('Student Annotation')
+      }
     end
   end
 

spec/helpers/gradebooks_helper_spec.rb

@@ -226,6 +226,11 @@ describe GradebooksHelper do
           expect(score_display).to eq '-'
         end
       end
+
+      it "shows an 'annotate' icon when the submission is a student annotation" do
+        submission.submission_type = 'student_annotation'
+        expect(score_icon['class']).to include 'icon-annotate'
+      end
     end
   end