feat: stop calling course blocks rest API and assume LS exists (#803)

- Assume that Learning Sequences is available (waffle has been
  removed)
- Stop calling course blocks API, which provided mostly duplicated
  information now.
- Refactor a bit to avoid needing to globally know which units
  exist in sequences. That is now provided just-in-time for only
  the current sequence.
- Add /first and /last URLs that you can use instead of unit IDs
  in URL paths, in service of the above point.

AA-1040
AA-1153

src/instructor-toolbar/InstructorToolbar.jsx

@@ -1,6 +1,5 @@
 import React, { useEffect, useState } from 'react';
 import PropTypes from 'prop-types';
-import { useSelector } from 'react-redux';
 import { getConfig } from '@edx/frontend-platform';
 
 import { ALERT_TYPES, AlertList } from '../generic/user-messages';
@@ -37,6 +36,14 @@ function getStudioUrl(courseId, unitId) {
   return urlFull;
 }
 
+function getLegacyWebUrl(canViewLegacyCourseware, courseId, unitId) {
+  if (!canViewLegacyCourseware || !unitId) {
+    return undefined;
+  }
+
+  return `${getConfig().LMS_BASE_URL}/courses/${courseId}/jump_to/${unitId}?experience=legacy`;
+}
+
 export default function InstructorToolbar(props) {
   // This didMount logic became necessary once we had a page that does a redirect on a quick exit.
   // As a result, it unmounts the InstructorToolbar (which will be remounted by the new component),
@@ -60,18 +67,7 @@ export default function InstructorToolbar(props) {
   } = props;
 
   const urlInsights = getInsightsUrl(courseId);
-  const urlLegacy = useSelector((state) => {
-    if (!canViewLegacyCourseware) {
-      return undefined;
-    }
-
-    if (!unitId) {
-      return undefined;
-    }
-
-    const activeUnit = state.models.units[props.unitId];
-    return activeUnit ? activeUnit.legacyWebUrl : undefined;
-  });
+  const urlLegacy = getLegacyWebUrl(canViewLegacyCourseware, courseId, unitId);
   const urlStudio = getStudioUrl(courseId, unitId);
   const [masqueradeErrorMessage, showMasqueradeError] = useState(null);
 

src/instructor-toolbar/InstructorToolbar.test.jsx

@@ -15,24 +15,27 @@ jest.mock('@edx/frontend-platform', () => ({
 getConfig.mockImplementation(() => originalConfig);
 
 describe('Instructor Toolbar', () => {
+  let courseware;
+  let models;
   let mockData;
   let axiosMock;
   let masqueradeUrl;
 
   beforeAll(async () => {
-    const store = await initializeTestStore({ excludeFetchSequence: true });
-    const { courseware, models } = store.getState();
-    mockData = {
-      courseId: courseware.courseId,
-      unitId: Object.values(models.units)[0].id,
-      canViewLegacyCourseware: true,
-    };
+    const store = await initializeTestStore();
+    courseware = store.getState().courseware;
+    models = store.getState().models;
 
     axiosMock = new MockAdapter(getAuthenticatedHttpClient());
     masqueradeUrl = `${getConfig().LMS_BASE_URL}/courses/${courseware.courseId}/masquerade`;
   });
 
   beforeEach(() => {
+    mockData = {
+      courseId: courseware.courseId,
+      unitId: Object.values(models.units)[0].id,
+      canViewLegacyCourseware: true,
+    };
     axiosMock.reset();
     axiosMock.onGet(masqueradeUrl).reply(200, { success: true });
     logUnhandledRequests(axiosMock);