Group livekitRoomItems$ by connection

The old reducer keyed items by service URL and mutated the accumulator's
entries in place, so a transport without a service URL could not be
represented and items were not safe to compare. Group members by their
Connection object instead and carry the whole transport on the item, which
the audio renderer now receives in place of a URL.

src/livekit/MatrixAudioRenderer.test.tsx

@@ -24,6 +24,7 @@ import { testAudioContext } from "../useAudioContext.test";
 import * as MediaDevicesContext from "../MediaDevicesContext";
 import { LivekitRoomAudioRenderer } from "./MatrixAudioRenderer";
 import {
+  exampleTransport,
   mockLocalParticipant,
   mockMediaDevices,
   mockRemoteParticipant,
@@ -118,7 +119,7 @@ function renderTestComponent(
       <LivekitRoomAudioRenderer
         validIdentities={participants.map((p) => p.identity)}
         livekitRoom={livekitRoom}
-        url={""}
+        transport={exampleTransport}
       />
     </MediaDevicesProvider>,
   );
@@ -150,7 +151,7 @@ it("should not render or warn for the local participant", () => {
       <LivekitRoomAudioRenderer
         validIdentities={[]}
         livekitRoom={{ remoteParticipants: new Map() } as unknown as Room}
-        url={""}
+        transport={exampleTransport}
       />
     </MediaDevicesProvider>,
   );
@@ -177,7 +178,7 @@ it("should warn only once per unexpected participant", () => {
       <LivekitRoomAudioRenderer
         validIdentities={[]}
         livekitRoom={{ remoteParticipants: new Map() } as unknown as Room}
-        url={""}
+        transport={exampleTransport}
       />
     </MediaDevicesProvider>,
   );