Denormalize buffer operations (#9026)

This should significantly reduce database load on redeploy.

Co-Authored-By: Max <max@zed.dev>
Co-Authored-By: Nathan <nathan@zed.dev>

Release Notes:

- Reduced likelihood of being disconnected during deploys

Co-authored-by: Max <max@zed.dev>
Co-authored-by: Nathan <nathan@zed.dev>

crates/collab/src/db/tables/buffer.rs

@@ -8,6 +8,9 @@ pub struct Model {
     pub id: BufferId,
     pub epoch: i32,
     pub channel_id: ChannelId,
+    pub latest_operation_epoch: Option<i32>,
+    pub latest_operation_lamport_timestamp: Option<i32>,
+    pub latest_operation_replica_id: Option<i32>,
 }
 
 #[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]