Message Previews: Drafts

### Your use case

#### What would you like to do?
1. Pin Rooms with drafts to the top of the Room list or respective section.
2. Indicate draft message.
#### Why would you like to do it?
Pinning rooms with drafts makes them easier to find and reduces the chance of forgotten unsent messages.

### Have you considered any alternatives?

Add 'Drafts' filter.

### Additional context

_No response_

Start by reading how the room list and its sections are rendered, and how draft messages are represented in the client. The issue asks for rooms with drafts to be pinnable or prioritized and for drafts to be indicated; it also mentions a Drafts filter as an alternative. Done means the chosen behavior makes rooms with unsent drafts easier to find and visibly identifies those drafts.

Written by the indexing model from the issue text.