Show edits for the most recent visible event in roomlist preview

[ara4n]

Your use case

What would you like to do?

Room previews should show the most recent visible event in a room, including any edits to it.

Why would you like to do it?

#2301 meant that edits are entirely ignored when showing the room preview. As a result, if you (or anyone else) sends a message and then fixes a typo in it, the room preview will show the typo'd message.

This feels incredibly flakey, as either the user infers:

• Sync has broken and they're seeing stale state from the server
• Or perhaps room previews aren't local-echoed, and we're waiting for a remote echo and the server is slow?
• Or perhaps the app is broken

How would you like to achieve it?

Only ignore edits when calculating room previews if they apply to old events; take them into account if they apply to the most recent visible event in the room.

See element-hq/element-x-ios#2683 for the concrete EXI bug for this.

Have you considered any alternatives?

No response

Additional context

It's unfortunate that this misbehaviour was added in Feb, and it's now May and it's still broken (perhaps due to not actually getting back on the radar properly)