feat: use atlas in make pull_translations (#325)

Changes
-------
 - Bump frontend-platform to bring `intl-imports.js` script
 - Move all i18n imports into `src/i18n/index.js` so `intl-imports.js` can
   override it with latest translations
 - Add `atlas` into `make pull_translations` when `OPENEDX_ATLAS_PULL`
   environment variable is set.
 - Refactored i18n utils into own file to avoid overwriting them by
   atlas

Refs: [FC-0012 project](https://openedx.atlassian.net/l/cp/XGS0iCcQ) implementing Translation Infrastructure OEP-58.

src/components/GradesView/EditModal/OverrideTable/AdjustedGradeInput/hooks.js

@@ -1,5 +1,5 @@
 import { actions, selectors } from 'data/redux/hooks';
-import { getLocalizedSlash } from 'i18n';
+import { getLocalizedSlash } from 'i18n/utils';
 
 const useAdjustedGradeInputData = () => {
   const possibleGrade = selectors.root.useEditModalPossibleGrade();

src/components/GradesView/EditModal/OverrideTable/AdjustedGradeInput/hooks.test.jsx

@@ -1,4 +1,4 @@
-import { getLocalizedSlash } from 'i18n';
+import { getLocalizedSlash } from 'i18n/utils';
 import { actions, selectors } from 'data/redux/hooks';
 import useAdjustedGradeInputData from './hooks';
 
@@ -17,7 +17,7 @@ jest.mock('data/redux/hooks', () => ({
     },
   },
 }));
-jest.mock('i18n', () => ({ getLocalizedSlash: jest.fn() }));
+jest.mock('i18n/utils', () => ({ getLocalizedSlash: jest.fn() }));
 
 const localizedSlash = 'localized-slash';
 getLocalizedSlash.mockReturnValue(localizedSlash);