🔧(frontend) enable dynacast optimizations

According to the documentation:

Dynacast dynamically pauses video layers that are
not being consumed by any subscribers, significantly
reducing publishing CPU and bandwidth usage.

Dynacast will be enabled if SVC codecs (VP9/AV1) are used.
Multi-codec simulcast requires dynacast

My goal is to reduce CPU and bandwidth usage for clients.

Dynacast is enabled both in OpenTalk and LiveKit demo app!

src/frontend/src/features/rooms/components/Conference.tsx

@@ -66,6 +66,7 @@ export const Conference = ({
   const roomOptions = useMemo((): RoomOptions => {
     return {
       adaptiveStream: true,
+      dynacast: true,
       publishDefaults: {
         videoCodec: 'vp9',
       },