Migrate recent lessons to Jotai

[didoesdigital]

This PR migrates "recent lessons" out of App.js and loadPersonalPreferences to Jotai.

One significant change here is that instead of updating "recent lessons" when setupLesson and stopLesson are called, Typey Type now updates recent lessons on the first keystroke of lesson. This change is mostly to isolate introduction of recent lesson Jotai atom to Lesson.tsx and not try to fit Jotai atoms into App.js. The user-facing behavioural change is not a big difference so I expect it will not be noticeable for most people.

This PR also removes:

• adds tests
• unused imports and variables
• adds some types and comments