Folks in Columbia Heights salivating for a burger and cajun fries can finally step into a Five Guys today. Located at the corner of 14th and Irving streets, the shop was already bustling with a hungry lunch-time crowd. Now, anyone exiting the west Columbia Heights Metro — surrounded on three sides with Potbelly’s, Pete’s Apizza and Five Guys — will be hard-pressed to not grab something to eat In Arlington, Michael Landrum continues to…