Make all lessons importable on codesandbox

* Create `src` subdir.
* Create `package.json`.
* Organize files as in lesson 00.

- [X] Lesson 00: https://github.com/FNNDSC/ami/tree/dev/lessons/00
- [ ] Lesson 01: https://github.com/FNNDSC/ami/tree/dev/lessons/01
- [ ] Lesson 02: https://github.com/FNNDSC/ami/tree/dev/lessons/02
- [ ] Lesson 03: https://github.com/FNNDSC/ami/tree/dev/lessons/03
- [ ] Lesson 04: https://github.com/FNNDSC/ami/tree/dev/lessons/04
- [ ] Lesson 05: https://github.com/FNNDSC/ami/tree/dev/lessons/05
- [ ] Lesson 06: https://github.com/FNNDSC/ami/tree/dev/lessons/06
- [ ] Lesson 07: https://github.com/FNNDSC/ami/tree/dev/lessons/07

Use lessons/00 as the reference layout, then inspect lessons/01 through lessons/07 and identify the files that need the same organization. Create the requested src subdirectories and package.json files, and verify that each lesson imports successfully in CodeSandbox.

Written by the indexing model from the issue text.