Fix export issue from thread module (#3451)

* Fix export issue from thread module

* separate type from class export

* follow the pattern of what other exports do

Author: Enrico Schwendig

src/matrix.ts

@@ -37,7 +37,7 @@ export * from "./models/event-timeline-set";
 export * from "./models/poll";
 export * from "./models/room-member";
 export * from "./models/room-state";
-export { ThreadEvent, ThreadEmittedEvents, ThreadEventHandlerMap, Thread } from "./models/thread";
+export * from "./models/thread";
 export * from "./models/typed-event-emitter";
 export * from "./models/user";
 export * from "./models/device";