Add a way to get byte_size

[avantgardnerio]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

While trying to make FlightSQL features work that require returning Flight Info Endpoints that require the size in bytes of record batches, it was observed the code to do this is presently located in DataFusion, not arrow.

Describe the solution you'd like

Move this handy function from DataFusion to Arrow.

Describe alternatives you've considered

I'll use DataFusion until this change percolates up.