re-implement Markdown

[osBins]

New UI does not support Markdown. Earlier the chatApp used markdown-it, the code for which still exists in client.js file but it is not linked to the messages how they are being showed in the new UI

[KossakowskaKarolina]

Hello, I would work on this one.
@osBins could you assign me to this? Or is it reserved for someone else?

[osBins]

Hi @KossakowskaKarolina, great! Assigning this issue to you.

[osBins]

Partially resolved.