Add window.scrollTo shim in Jest

**Why?**
This way needed by `job_app_spec`

spec/frontend/helpers/dom_shims/index.js

 import './get_client_rects';
 import './inner_text';
+import './window_scroll_to';

spec/frontend/helpers/dom_shims/window_scroll_to.js

+window.scrollTo = jest.fn();