Motivation:
Currently calculateSize method in AbstractTrafficShapingHandler calculates size for object of type ByteBuf or ByteBufHolder. Adding a check for FileRegion, makes it possible to do traffic shaping for FileRegion objects as well
Modification:
Check if object to be sent is of type FileRegion, if yes calculate the size using its count() method.
Co-authored-by: Dinesh Joshi <dinesh.joshi@apple.com>