Do not react on already observed buffer edits' versions

[SomeoneToIgnore]

If I apply

diff --git a/crates/action_log/src/action_log.rs b/crates/action_log/src/action_log.rs
index 404fb3616d..ece063c34f 100644
--- a/crates/action_log/src/action_log.rs
+++ b/crates/action_log/src/action_log.rs
@@ -223,6 +223,7 @@ impl ActionLog {
             futures::select_biased! {
                 buffer_update = buffer_updates.next() => {
                     if let Some((author, buffer_snapshot)) = buffer_update {
+                        dbg!(&author);
                         Self::track_edits(&this, &buffer, author, buffer_snapshot, cx).await?;
                     } else {
                         break;

on top of main, User and Agent will always interleave.

This happens because action_log does updates on Entity<Buffer> which is a current editor's buffer, tracked, and updated by agent output (acp or regular threads) — those updates come back as BufferEvent::Edited event after each agent's edit and forces unnecessary computations.

Instead, update tracked buffer's version after each agent update report to only react on one, Agent-authored, edit events.

Release Notes:

• N/A