* refactor: use React Query to load waffle flags
* test: add test case
* fix: more clear handling of data loading and fallbacks
* refactor: simplify handling of useReactMarkdownEditor
* test: use new mockWaffleFlags() helper
* test: simplify test mocks in hooks.test.js
* refactor: avoid duplicating flag names, clarify how defaults work
Simplifies a bunch of test code by converting it to use our handy testUtils module.
None of the app code is change, just test code. And none of the test cases are modified in any meaningful way - this just simplifies the setup/cleanup significantly.
Introduces the ability to utilize SPA functionality when the relevant waffle flags are enabled for current MFE pages. When any new MFE page is loaded, a request is made to retrieve the waffle flags. This includes both global waffle flags related to MFE Authoring pages, as well as waffle flags specific to the current course.
