core_timing: Use better reference tracking for EventType. (#3159)

* core_timing: Use better reference tracking for EventType.

- Moves ownership of the event to the caller, ensuring we don't fire events for destroyed objects.
- Removes need for unique names - we won't be using this for save states anyways.

src/core/memory/cheat_engine.cpp

@@ -186,7 +186,7 @@ CheatEngine::~CheatEngine() {
 }
 
 void CheatEngine::Initialize() {
-    event = core_timing.RegisterEvent(
+    event = Core::Timing::CreateEvent(
         "CheatEngine::FrameCallback::" + Common::HexToString(metadata.main_nso_build_id),
         [this](u64 userdata, s64 cycles_late) { FrameCallback(userdata, cycles_late); });
     core_timing.ScheduleEvent(CHEAT_ENGINE_TICKS, event);