test: Visual testing for Cornerstone and VTK (#1169)

* Visual testing for Cornerstone and VTK

* Fix for CI

* Review fix: Removed cornerstone function and added snapshot description

* Added snapshot description

* Fix for CI

platform/viewer/cypress/integration/common/OHIFStudyViewer.spec.js

@@ -11,8 +11,8 @@ describe('OHIF Study Viewer Page', function() {
   });
 
   it('checks if series thumbnails are being displayed', function() {
-    cy.screenshot();
-    cy.percyCanvasSnapshot('Series Thumbnails');
+    cy.screenshot('Series Thumbnails - Should Display Thumbnails');
+    cy.percyCanvasSnapshot('Series Thumbnails - Should Display Thumbnails');
 
     cy.get('[data-cy="thumbnail-list"]')
       .its('length')
@@ -291,6 +291,10 @@ describe('OHIF Study Viewer Page', function() {
       });
     });
 
+    // Visual comparison
+    cy.screenshot('About modal - Should display modal');
+    cy.percyCanvasSnapshot('About modal - Should display modal');
+
     //close modal
     cy.get('.close').click();
     cy.get('@aboutOverlay').should('not.be.enabled');