closes ENG-678
The comments block is typically shown at the bottom of a post so it doesn't make sense to eagerly fetch comments from the API when we don't know if the comments block will even be viewed. By lazy-loading the data only when the comments block comes into view we can reduce both data usage for visitors and load on the site.
- uses IntersectionObserver API to delay comments app initialisation until the comments block has scrolled into view
- updated all iframe-related components to forward a `ref` so we can use the `<iframe>` element reference inside the `App` component
refs https://github.com/TryGhost/Product/issues/3504
- App component now uses React hooks intead of React class component
- App is now written in TypeScript
- All JavaScript is now removed from the Comments-UI project
- Removed `PopupNotification` because these were never displayed
- Removed `action` from AppContext (never used)
- Moved options parsing out of `index.ts` into a separate utility file,
similar to the signup-form
- Improved reliability of some editor tests by always waiting for the
editor to be focused (was not always the case) + added an utility method
for this
refs https://github.com/TryGhost/Product/issues/3504
- When you are logged in as an admin, but not as a member, no buttons
showed (discovered in new e2e tests)
- Added E2E tests for admin actions
