feat: section list and new section button

Also refactor api and hooks

fix: publish button behaviour and card header tests

fix: warning in highlights and publish modal test

fix: courseoutline tests

test: add test for new section functionality

fix(lint): lint issues

refactor: remove unnecessary css in CardHeader

refactor: rename emptyPlaceholder test file

refactor: replace ternary operator with 'and' condition

refactor: add black color to expand/collapse button

refactor: display only changed subsection and units in publish modal

refactor: update messages and css

refactor: wrap urls in function call

refactor: fix jsdoc types

refactor: use helmet for document title

src/generic/processing-notification/data/slice.js

@@ -1,9 +1,11 @@
 /* eslint-disable no-param-reassign */
 import { createSlice } from '@reduxjs/toolkit';
 
+import { NOTIFICATION_MESSAGES } from '../../../constants';
+
 const initialState = {
   isShow: false,
-  title: '',
+  title: NOTIFICATION_MESSAGES.empty,
 };
 
 const slice = createSlice({