feat: add AccountsChanged and AccountsItemChanged events (#6118)

- **feat: add `AccountsChanged` and `AccountsItemChanged` events**
- **emit event and add tests**

closes #6106

TODO:
- [x] test receiving synced config from second device
- [x] bug: investigate how to delay the configuration event until it is
actually configured - because desktop gets the event but still shows
account as if it was unconfigured, maybe event is emitted before the
value is written to the database?
- [x] update node bindings constants

src/config.rs

@@ -791,6 +791,12 @@ impl Context {
                 self.sql.set_raw_config(key.as_ref(), value).await?;
             }
         }
+        if matches!(
+            key,
+            Config::Displayname | Config::Selfavatar | Config::PrivateTag
+        ) {
+            self.emit_event(EventType::AccountsItemChanged);
+        }
         if key.is_synced() {
             self.emit_event(EventType::ConfigSynced { key });
         }