Fix notes unread status (#7643)

1. The client-side comparison was wrong
2. The server never told the client about the version it remembered
3. The server generated broken timestamps in some cases

Release Notes:

- Fixed the notes/chat appearing as unread too often

**or**

- N/A

crates/collab/src/tests/test_server.rs

@@ -10,6 +10,7 @@ use channel::{ChannelBuffer, ChannelStore};
 use client::{
     self, proto::PeerId, Client, Connection, Credentials, EstablishConnectionError, UserStore,
 };
+use collab_ui::channel_view::ChannelView;
 use collections::{HashMap, HashSet};
 use fs::FakeFs;
 use futures::{channel::oneshot, StreamExt as _};
@@ -766,6 +767,16 @@ pub fn join_channel_call(cx: &mut TestAppContext) -> Task<anyhow::Result<()>> {
     room.unwrap().update(cx, |room, cx| room.join_call(cx))
 }
 
+pub fn open_channel_notes(
+    channel_id: u64,
+    cx: &mut VisualTestContext,
+) -> Task<anyhow::Result<View<ChannelView>>> {
+    let window = cx.update(|cx| cx.active_window().unwrap().downcast::<Workspace>().unwrap());
+    let view = window.root_view(cx).unwrap();
+
+    cx.update(|cx| ChannelView::open(channel_id, None, view.clone(), cx))
+}
+
 impl Drop for TestClient {
     fn drop(&mut self) {
         self.app_state.client.teardown();