Core/EventProcessor: std::chrono-ify CalculateTime

uint64 CalculateTime(uint64 t_offset) has been replaced with Milliseconds CalculateTime(Milliseconds t_offset).
Also add the std::chrono-ified overload void AddEvent(BasicEvent*, Milliseconds, bool)

(cherry picked from commit 92a02a5c87)

src/common/Utilities/EventProcessor.cpp

@@ -75,7 +75,7 @@ void EventProcessor::Update(uint32 p_time)
 
         // Reschedule non deletable events to be checked at
         // the next update tick
-        AddEvent(event, CalculateTime(1), false);
+        AddEvent(event, CalculateTime(1ms), false);
     }
 }