Upgrade eslint-plugin-matrix-org to 1.2.1

This upgrade came with a number of new lints that needed to be fixed across the code base. Primarily: explicit return types on functions, and explicit visibility modifiers on class members.

src/livekit/useLiveKit.ts

@@ -156,7 +156,7 @@ export function useLiveKit(
   useEffect(() => {
     // Sync the requested devices with LiveKit's devices
     if (room !== undefined && connectionState === ConnectionState.Connected) {
-      const syncDevice = (kind: MediaDeviceKind, device: MediaDevice) => {
+      const syncDevice = (kind: MediaDeviceKind, device: MediaDevice): void => {
         const id = device.selectedId;
         if (id !== undefined && room.getActiveDevice(kind) !== id) {
           room