DETROIT — With the push of a button, a long-armed robot steadily piped out a concrete mixture, programmed to follow a pattern that will create the exterior wall of a house. Dozens of these segments would eventually be transported from a facility in Detroit and connected to build a 1,000-square-foot, two-bedroom home on the city’s east side. Detroit-based nonprofit Citizen Robotics, creator of the 3D printed house, and the Michigan State Housing Development Authority, celebrated the start of construction Tuesday afternoon for the house, which they tout will be the first of its kind in the city….