switch to using own event system

src/lib/eventsystem/event/ArenaStartRequestedEvent.h

@@ -0,0 +1,10 @@
+#pragma once
+
+#include "Event.h"
+
+class ArenaStartRequestedEvent : public Event
+{
+public:
+    explicit ArenaStartRequestedEvent(int arenaIndex) : arenaIndex(arenaIndex) {}
+    const int arenaIndex;
+};