Move shared editor state from Redux to Context

The editors use Redux to store their state, and it can be hard to reason about.

Expanding on previous work, state that's used by all the editors (i.e. the app state) should be moved into EditorContext.

Example:

🛑 Old:

const learningContextId = useSelector(selectors.app.learningContextId);

🛑 Very old!

mapStateToProps = (state) => ({
  learningContextId: selectors.app.learningContextId(state), ...

🛑 Very old! (no need to pass these as props ("prop drilling"); just get them from context wherever you need them)

VideoSelector.propTypes = {
  learningContextId: PropTypes.string.isRequired, ...

✅ New:

const { learningContextid } = useEditorContext();

Note: I'm not sure if everything in the app state is used by more than one editor. So check as you go.

PRs:

• https://github.com/openedx/frontend-app-authoring/pull/2398

Start with src/editors/data/redux/index.ts, especially the app state, and src/editors/EditorContext.tsx. Search the editors for uses of app state and determine which values are shared; done means shared values come from EditorContext rather than Redux or prop drilling, with the existing pull request providing relevant context.