fix: 🐛 Fix ghost shadow on thumb (#1113)

* fix: 🐛 Fix ghost shadow on thumb

Updated react-dnd package for the lates. Refactored thumbnail component

Closes: 1087

* feat: 🎸 Code review

Set flex instead of float. Add cypress tag to thumb container

* feat: 🎸 Code review. Revised style when no description

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

@@ -8,7 +8,7 @@ describe('ViewerRouting', () => {
   });
 
   // it('thumbnails list has more than 2 items', () => {
-  //   cy.get('.scrollable-study-thumbnails div.ThumbnailEntryContainer')
+  //   cy.get('.scrollable-study-thumbnails div.thumbnail-container')
   //     .its('length')
   //     .should('be.gte', 2);
   // });