feat: add deprecation warning to create legacy library form [FC-0123] (#2963)

--------

Co-authored-by: Kyle McCormick <[email protected]>

Author: rpenido

src/library-authoring/create-legacy-library/CreateLegacyLibrary.tsx

@@ -2,14 +2,16 @@ import { StudioFooterSlot } from '@edx/frontend-component-footer';
 import { getConfig } from '@edx/frontend-platform';
 import { useIntl } from '@edx/frontend-platform/i18n';
 import {
+  Alert,
   Container,
   Form,
   Button,
   StatefulButton,
   ActionRow,
 } from '@openedx/paragon';
+import { Warning } from '@openedx/paragon/icons';
 import { Formik } from 'formik';
-import { useNavigate } from 'react-router-dom';
+import { useNavigate, Link } from 'react-router-dom';
 import * as Yup from 'yup';
 import classNames from 'classnames';
 
@@ -100,6 +102,20 @@ export const CreateLegacyLibrary = ({
             title={intl.formatMessage(legacyMessages.createLibrary)}
           />
         )}
+        <Alert variant="warning" icon={Warning}>
+          <Alert.Heading>{intl.formatMessage(legacyMessages.warningTitle)}</Alert.Heading>
+          {intl.formatMessage(legacyMessages.warningBody, {
+            libraryLink: (
+              <Alert.Link
+                as={Link}
+                // @ts-ignore
+                to="/libraries"
+              >
+                {intl.formatMessage(legacyMessages.warningLibraryFeature)}
+              </Alert.Link>
+            ),
+          })}
+        </Alert>
         <Formik
           initialValues={{
             displayName: '',

src/library-authoring/create-legacy-library/messages.ts

@@ -11,6 +11,21 @@ const messages = defineMessages({
     defaultMessage: 'Legacy library name',
     description: 'Label for the title field when creating a legacy library.',
   },
+  warningTitle: {
+    id: 'course-authoring.library-authoring.create-legacy-library.warning.title',
+    defaultMessage: 'You are creating content in a deprecated format',
+    description: 'Warning to discourage users from creating a new Legacy Library',
+  },
+  warningBody: {
+    id: 'course-authoring.library-authoring.create-legacy-library.warning.body',
+    defaultMessage: 'Legacy libraries will be unsupported in Willow. Any content you create in a legacy library will soon need to be migrated. Consider using the {libraryLink} instead.',
+    description: 'Warning to discourage users from creating a new Legacy Library',
+  },
+  warningLibraryFeature: {
+    id: 'course-authoring.library-authoring.create-legacy-library.warning.library-feature',
+    defaultMessage: 'Library feature',
+    description: 'Link to the Libraries feature page',
+  },
   createLibraryButton: {
     id: 'course-authoring.library-authoring.create-legacy-library.form.create-library.button',
     defaultMessage: 'Create legacy library',