Expire video member events after 1 hour (#8776)

* Expire video member events after 1 hour

* Iterate based on feedback

* Validate the types of video member events better

* Even more parentheses

test/components/structures/VideoRoomView-test.tsx

@@ -95,7 +95,10 @@ describe("VideoRoomView", () => {
 
         // All devices should have been removed
         expect(cli.sendStateEvent).toHaveBeenLastCalledWith(
-            "!1:example.org", VIDEO_CHANNEL_MEMBER, { devices: [] }, cli.getUserId(),
+            "!1:example.org",
+            VIDEO_CHANNEL_MEMBER,
+            { devices: [], expires_ts: expect.any(Number) },
+            cli.getUserId(),
         );
     });