chore(ui): Remove SlidingSyncRoomExt.

This patch removes the `matrix_sdk_ui::timeline::SlidingSyncRoomExt`
trait as it's no longer necessary since `room_list::Room::latest_event`
no longer uses `SlidingSyncRoom` to fetch the latest event.

Author: Hywan

crates/matrix-sdk-ui/src/timeline/mod.rs

@@ -78,7 +78,6 @@ mod pagination;
 mod polls;
 mod reactions;
 mod read_receipts;
-mod sliding_sync_ext;
 #[cfg(test)]
 mod tests;
 #[cfg(feature = "e2e-encryption")]
@@ -102,7 +101,6 @@ pub use self::{
     pagination::LiveBackPaginationStatus,
     polls::PollResult,
     reactions::ReactionSenderData,
-    sliding_sync_ext::SlidingSyncRoomExt,
     traits::RoomExt,
     virtual_item::VirtualTimelineItem,
 };

crates/matrix-sdk-ui/src/timeline/sliding_sync_ext.rs

@@ -343,10 +343,6 @@ copies accordingly. Because of where the loop sits in the stack, that can
 be a bit tedious though, so lists and rooms have an additional way of
 subscribing to updates via [`eyeball`].
 
-The `Timeline` one can receive per room by calling `.timeline()` (from
-`matrix_sdk_ui::timeline::SlidingSyncRoomExt`) will be populated with the
-currently cached timeline events.
-
 ## Caching
 
 All room data, for filled but also _invalidated_ rooms, including the entire