refactor(chapter-thumbnail-menu-button): Update to be more inline with `video.js`.
refactor(chapter-thumbnail-menu-button): Update to be more inline with `video.js`.

Original implementation mimic'd the old version of the `ChaptersButton`, this updates the component to be more inline with the existing `ChaptersButton`.

- Extract `findChaptersTrack`
- Extract `setTrack`
- Do not cache `menu`
- Leverage `super.update` https://github.com/videojs/video.js/blob/v5.19.1/src/js/menu/menu-button.js#L42 (clears out the old `menu`)

chemoish/videojs-chapter-thumbnails,chemoish/videojs-chapter-thumbnails