docs: source code documentation with `typedoc`

[ascariandrea]

Summary

I added typedoc so we can also start documenting the source code. It still needs some tweaking and proper placement in header and sidebars, but we can do this later.

Changelog

[docs] Source code documentation with typedoc

Test Plan

docker-compose up -d mongodb
./docs/scripts/build.sh
yarn docs start

On http://localhost:3000, you should see:

• [x] a "Source" dropdown in the header
  • [x] a "@taboule" item in the dropdown
  • [x] a "@shared" item in the dropdown
  • [x] a "@yttrex/shared" item in the dropdown
  • [x] a "@yttrex/backend" item in the dropdown
  • [x] a "@tktrex/shared" item in the dropdown
  • [x] a "@tktrex/backend" item in the dropdown