Remove unused preference types
Remove unused preference types

Json and Array types were intended to be valid preference types
but got never correctly supported and tested. They are getting
removed for avoiding unsafe use of preferences.

They can later re-implemented, probably using a packge for handling
model preferences.

timegridio/timegrid,alariva/timegrid,alariva/timegrid,alariva/timegrid,timegridio/timegrid,timegridio/timegrid,alariva/timegrid