init app of test arena

asf-cloud-server/testarena/backend/app/socket_manager.py

@@ -0,0 +1,22 @@
+from fastapi import WebSocket
+from typing import List
+
+class ConnectionManager:
+    def __init__(self):
+        self.active_connections: List[WebSocket] = []
+
+    async def connect(self, websocket: WebSocket):
+        await websocket.accept()
+        self.active_connections.append(websocket)
+
+    def disconnect(self, websocket: WebSocket):
+        self.active_connections.remove(websocket)
+
+    async def broadcast(self, message: str):
+        for connection in self.active_connections:
+            try:
+                await connection.send_text(message)
+            except:
+                self.disconnect(connection)
+
+manager = ConnectionManager()