Undeprecate UnknownArrayHandle::GetNumberOfComponents

This method was originally deprecated to avoid confusion with the
indexing of the components in `ExtractComponent`. However, there might
be good reason to want to know the non-flat number of components, so
maybe getting rid of it is not a great idea. Unmark the method as
deprecated, at least for now.
7 jobs for undeprecate-unknownarrayhandle-numberofcomponents