Load Puzzles from Lichess API

[FeXd]

Followup to #5, attempt to fetch puzzles from Lichess API.

[FeXd]

Lichess API: https://lichess.org/api

Important

All requests are rate limited using various strategies, to ensure the API remains responsive for everyone. Only make one request at a time. If you receive an HTTP response with a 429 status, please wait a full minute before resuming API usage.

Puzzles endpoints: https://lichess.org/api#tag/Puzzles

Example: https://lichess.org/api#tag/Puzzles

Get a puzzle by its ID

Example: https://lichess.org/api/puzzle/0pqXI

Does this mean we are going to need to store our own list of puzzle IDs along with their ratings? Oh dear.