Bw/unit splitup (#1134)

* refactor: break Unit component into smaller unit-tested parts

* feat: save scroll position on video fullscreen exit

* chore: remove swap file

package.json

@@ -35,6 +35,7 @@
     "@edx/frontend-lib-special-exams": "2.19.1",
     "@edx/frontend-platform": "4.3.0",
     "@edx/paragon": "20.28.4",
+    "@edx/react-unit-test-utils": "npm:@edx/react-unit-test-utils@1.5.3",
     "@fortawesome/fontawesome-svg-core": "1.3.0",
     "@fortawesome/free-brands-svg-icons": "5.15.4",
     "@fortawesome/free-regular-svg-icons": "5.15.4",
@@ -48,7 +49,7 @@
     "js-cookie": "3.0.1",
     "lodash.camelcase": "4.3.0",
     "prop-types": "15.8.1",
-    "query-string": "7.1.3",
+    "query-string": "^7.1.3",
     "react": "16.14.0",
     "react-dom": "16.14.0",
     "react-helmet": "6.1.0",