Integrate virtual chats using MessageKit

[twostraws]

When these lessons are used inside the 100 Days of Swift and 100 Days of SwiftUI, they sometimes include virtual chats that help re-enforce what has been learned in a more casual way. I'd love to see these chats incorporated into Unwrap using something like MessageKit. I mean, technically there's nothing stopping us designing the whole thing from scratch without the extra dependency, because all we need is a scrolling list of message bubbles – there's no free text entry, or need for user avatars.

The chats all follow a precise format from a use's perspective:

• They look like an iMessage conversation.
• Both sides of the chat are fixed – the user can't enter custom text.
• After the user presses send it looks like they are sending before the reply appears.
• They all end after a few messages - they are quite brief.

From a code perspective, they are stored as JSON, again in a precise format. Here's an example, but I have 9 in total we can release.

They naturally sit at the end of a particular section of the course, e.g. after all the sections in Simple Types. We could make them stand out in the table using a chat icon rather than a check mark, perhaps – I'm happy to try a range of designs.