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/rtcSessionHelpers.ts

@@ -33,7 +33,7 @@ function makeFocus(livekitAlias: string): LivekitFocus {
   };
 }
 
-export function enterRTCSession(rtcSession: MatrixRTCSession) {
+export function enterRTCSession(rtcSession: MatrixRTCSession): void {
   PosthogAnalytics.instance.eventCallEnded.cacheStartCall(new Date());
   PosthogAnalytics.instance.eventCallStarted.track(rtcSession.room.roomId);
 
@@ -47,7 +47,7 @@ export function enterRTCSession(rtcSession: MatrixRTCSession) {
   rtcSession.joinRoomSession([makeFocus(livekitAlias)]);
 }
 
-export function leaveRTCSession(rtcSession: MatrixRTCSession) {
+export function leaveRTCSession(rtcSession: MatrixRTCSession): void {
   //groupCallOTelMembership?.onLeaveCall();
   rtcSession.leaveRoomSession();
 }