feat(sdk,ui): Add EventsOrigin::Pagination.

This patch adds the `Pagination` variant to the `EventsOrigin` enum.
Not something really mandatory and that is likely to fix a bug, but it's
now correct.

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

@@ -280,6 +280,7 @@ impl TimelineBuilder {
                                 diffs,
                                 match origin {
                                     EventsOrigin::Sync => RemoteEventOrigin::Sync,
+                                    EventsOrigin::Pagination => RemoteEventOrigin::Pagination,
                                 }
                             ).await;
                         }

crates/matrix-sdk/src/event_cache/mod.rs

@@ -570,6 +570,9 @@ pub enum RoomEventCacheUpdate {
 pub enum EventsOrigin {
     /// Events are coming from a sync.
     Sync,
+
+    /// Events are coming from pagination.
+    Pagination,
 }
 
 #[cfg(test)]

crates/matrix-sdk/src/event_cache/pagination.rs

@@ -235,7 +235,7 @@ impl RoomPagination {
         if !sync_timeline_events_diffs.is_empty() {
             let _ = self.inner.sender.send(RoomEventCacheUpdate::UpdateTimelineEvents {
                 diffs: sync_timeline_events_diffs,
-                origin: EventsOrigin::Sync,
+                origin: EventsOrigin::Pagination,
             });
         }