Parse markdown to blocks in Slack

[GAsplund]

Key Features

• Display for which group a news post was posted for
• Closes As a Slack / Discord reader, I want images to be included in news post notifications, so that I can read them properly #119
• Parse markdown into Block Kit for news post notifiers (images, links, and formatting works again!)
• Merge consecutive section blocks (to prevent unnecessary "See more" links)
• Display large text for post title
• Show permalink underneath title
• Handle cases to prevent invalid attachments/request payloads

Screenshots

Known Issues

• There was barely any porting work done for Discord webhooks
  • Since we don't use it currently, I'm personally fine with this

[simon-wg]

Lgtm

[simon-wg]

Lgtm still 👍