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/useECConnectionState.ts

@@ -119,7 +119,7 @@ export function useECConnectionState(
         `SFU config changed! URL was ${currentSFUConfig.current?.url} now ${sfuConfig?.url}`
       );
 
-      (async () => {
+      (async (): Promise<void> => {
         setSwitchingFocus(true);
         await livekitRoom?.disconnect();
         setIsInDoConnect(true);