Who is the Motherf**ker who left a hat in Veronica's apartment (and, by extension, who is f**king Veronica)? This is the question that sets up the action in THE MOTHERF**KER WITH THE HAT, the Stephen Adly Guirgis-written and Anna D. Shapiro-helmed play which opened tonight at the Shoenfeld. It's a quick, breathless ride that carries with it themes of infidelity, alcoholism and addiction, the limits and rules of friendship, and the trials and tribulations