added column-reverse to also calcualte gap height (#3763)
added column-reverse to also calcualte gap height (#3763)

* added column-reverse to also calcualte gap height

* need to also add directionProp === column-reverse

* add column-reverse

Co-authored-by: Shimi <91d179157e4fb8ed4d1a2fb40c584b1ced338ef7@gmail.com>

HewlettPackard/grommet,grommet/grommet,grommet/grommet,HewlettPackard/grommet,grommet/grommet,HewlettPackard/grommet