Can a built-in dishwasher be plugged into a receptacle?
It can definitely be plugged into a receptacle.  Some new dish washers come with the cord already attached and some give you directions.  Almost all require a GFCI outlet and you need to read what size circuit you need.  

My experience in the past 3-4 years.  Installed 6 dishwashers.  1 had cord already on it - which is kind of a pain because often there is no outlet.  The other 5 all had instructions that said it allowed for wiring to be turned into cord.  1 we did that because it made sense - used outlet behind fridge (not the same outlet as fridge).  Just look up manufacturer's instructions online if you have any questions but the short answer is YES.