Add support for getting vec sizes of unknown arrays when runtime selected

The GetNumberOfComponents and GetNumberOfComponentsFlat methods in UnknownArrayHandle have been updated to correctly report the number of components in special ArrayHandles where the Vec sizes of the values are not selected until runtime.

Previously, these methods always reported 0 because the value type could not report the size of the Vec. The lookup has been modified to query the ArrayHandle's Storage for the number of components where supported. Note that this only works on Storage that provides a method to get the runtime Vec size. If that is not provided, as will be the case if the number of components can vary from one value to the next, it will still report 0.

This feature is implemented by looking for a method named GetNumberOfComponents is the Storage class for the ArrayHandle. If this method is found, it is used to query the size at runtime.