Even now, “President Donald Trump,” is still a phrase that requires conceptual gymnastics — a leap from the tabloid depths to the heights of power. Consider a pair of scenes, in a pair of courtrooms, Thursday morning. Promptly at 10 a.m., in Washington, to the ritual incantation of “Oyez! Oyez! Oyez!” nine black robed justices of the Supreme Court filed in to hear arguments in a case that could determine whether a president can be prosecuted for committing crimes while in office.