MM-56071: Thread presence indicator (#25694)

We also track the channelID of the thread opened.

Additionally on every connection create or re-connect
with an existing queue, we reset the active state to empty
to avoid any edge-cases.

https://mattermost.atlassian.net/browse/MM-56071

```release-note
NONE
```

webapp/platform/client/src/websocket.ts

@@ -396,6 +396,13 @@ export default class WebSocketClient {
         this.sendMessage('presence', data, callback);
     }
 
+    updateActiveThread(channelId: string, callback?: (msg: any) => void) {
+        const data = {
+            thread_channel_id: channelId,
+        };
+        this.sendMessage('presence', data, callback);
+    }
+
     userUpdateActiveStatus(userIsActive: boolean, manual: boolean, callback?: () => void) {
         const data = {
             user_is_active: userIsActive,