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/MediaDevicesContext.tsx

@@ -52,7 +52,7 @@ export interface MediaDevices {
 function useObservableState<T>(
   observable: Observable<T> | undefined,
   startWith: T
-) {
+): T {
   const [state, setState] = useState<T>(startWith);
   useEffect(() => {
     // observable state doesn't run in SSR
@@ -207,7 +207,8 @@ export const MediaDevicesProvider: FC<Props> = ({ children }) => {
   );
 };
 
-export const useMediaDevices = () => useContext(MediaDevicesContext);
+export const useMediaDevices = (): MediaDevices =>
+  useContext(MediaDevicesContext);
 
 /**
  * React hook that requests for the media devices context to be populated with
@@ -215,7 +216,10 @@ export const useMediaDevices = () => useContext(MediaDevicesContext);
  * default because it may involve requesting additional permissions from the
  * user.
  */
-export const useMediaDeviceNames = (context: MediaDevices, enabled = true) =>
+export const useMediaDeviceNames = (
+  context: MediaDevices,
+  enabled = true
+): void =>
   useEffect(() => {
     if (enabled) {
       context.startUsingDeviceNames();