Replace Article of the Day feature from the legacy bot

[christolis]

Describe the feature

For some context, the original Discord bot of the Learn English™ Discord server would send a daily message in a certain channel with a randomly-chosen article for users to read. We should include that feature in this bot.

• To make this feature even better than the original one, we could generate questions for each article and have users optionally answer them in a direct message text channel with the bot after they press a "⁉️ Quiz" button right below the article's embed (this should be similar with how users are able to practice with words from their journal).
  • Users who solve the questions from a daily article should get awarded with 20XP points that can count to their streak. They should not be able to solve it more than once, or solve articles that are older than 1 week.
  • Users get the same experience points, regardless of how many mistakes they can make.

Thoughts

• From which data provider would these daily articles get fetched?
• Maybe we could store user statistics in the database, so that in a future version we can display that data.