[core] move event creation to attached Core::System, remove unused atomics/prevent false share on Core::Timing

Signed-off-by: lizzie <lizzie@eden-emu.dev>

src/core/core.cpp

@@ -969,4 +969,8 @@ void System::ApplySettings() {
     }
 }
 
+std::shared_ptr<Core::Timing::EventType> System::CreateEvent(std::string name, Core::Timing::TimedCallback&& callback) {
+    return std::make_shared<Core::Timing::EventType>(std::move(callback), std::move(name));
+}
+
 } // namespace Core