When a time is set on SunTime, it should not emit an event on Start

[mvriel]

On https://github.com/Netherlands3D/Sun/blob/main/Runtime/Scripts/SunTime.cs#L64, the Apply method is called and will think the time has changed and thus emit an event. This can cause an exception NullReferenceException: Object reference not set to an instance of an object DateTimeExtract.ExtractFromDateTime (System.DateTime dateTime) because other parts of the application their Start's haven't completed yet.

The fix for this is to only emit an event for when the time has changed if it really has; and not upon initialisation