In the midst of so much gloom, a little happy news out of Ukraine: Yelena Akhtiorskaya can’t resolve the separatist crisis or repel Vladimir Putin, but this 28-year-old writer from Odessa subordinates the violence of nations for a moment and offers the balm of laughter. Her first novel, “Panic in a Suitcase,” is equal parts borscht stew and Borscht Belt — an immigration comedy that can’t tell whether it’s leaving or coming to America.