Fix Rust Chat App Tutorial not showing messages of other users live (#4588)

# Description of Changes

This fixes an Issue in the Rust [Chat App
Tutorial](https://spacetimedb.com/docs/tutorials/chat-app#creating-the-client),
that is caused by the [Event Type
Changes](https://spacetimedb.com/docs/upgrade/?client-language=rust&server-language=rust#event-type-changes)
in 2.0

This resulted in other clients not receiving new messages, since they
are now Event::Transaction and no longer included within the
Event::Reducer

# API and ABI breaking changes

<!-- If this is an API or ABI breaking change, please apply the
corresponding GitHub label. -->
I don't think any? I only changed a tutorial, the real change was in 2.0

# Expected complexity level and risk

1

# Testing

- [x] I ran the Tutorial app with these changes and messages started to
appear as expected on the second client when writing something on the
first.



There might be more places where this is an Issue, I just noticed this
one while following the Tutorial.

---------

Signed-off-by: Frederik <39029799+OMGeeky@users.noreply.github.com>
Co-authored-by: Zeke Foppa <196249+bfops@users.noreply.github.com>
Co-authored-by: Phoebe Goldman <phoebe@clockworklabs.io>

Author: 3 people

docs/docs/00100-intro/00300-tutorials/00100-chat-app.md

@@ -2556,7 +2556,7 @@ fn on_user_updated(_ctx: &EventContext, old: &User, new: &User) {
 
 #### Print messages
 
-When we receive a new message, we'll print it to standard output, along with the name of the user who sent it. Keep in mind that we only want to do this for new messages, i.e. those inserted by a `send_message` reducer invocation. We have to handle the backlog we receive when our subscription is initialized separately, to ensure they're printed in the correct order. To that effect, our `on_message_inserted` callback will check if the ctx.event type is an `Event::Reducer`, and only print in that case.
+When we receive a new message, we'll print it to standard output, along with the name of the user who sent it. Keep in mind that we only want to do this for new messages, i.e. those inserted by a `send_message` reducer invocation. We have to handle the backlog we receive when our subscription is initialized separately, to ensure they're printed in the correct order. To that effect, our `on_message_inserted` callback will check if the ctx.event type is an `Event::Reducer` (new local messages) or `Event::Transaction` (new messages from others), and only print in that case.
 
 To find the `User` based on the message's `sender` identity, we'll use `ctx.db.user().identity().find(..)`, which behaves like the same function on the server.
 
@@ -2569,7 +2569,7 @@ To `src/main.rs`, add:
 ```rust
 /// Our `Message::on_insert` callback: print new messages.
 fn on_message_inserted(ctx: &EventContext, message: &Message) {
-    if let Event::Reducer(_) = ctx.event {
+    if matches!(ctx.event, Event::Reducer(_) | Event::Transaction) {
         print_message(ctx, message)
     }
 }

templates/chat-console-rs/src/main.rs

@@ -140,7 +140,7 @@ fn on_user_updated(_ctx: &EventContext, old: &User, new: &User) {
 
 /// Our `Message::on_insert` callback: print new messages.
 fn on_message_inserted(ctx: &EventContext, message: &Message) {
-    if !matches!(ctx.event, Event::SubscribeApplied) {
+    if matches!(ctx.event, Event::Reducer(_) | Event::Transaction) {
         print_message(ctx, message);
     }
 }