We can thank Watergate and the fall of Richard Nixon for numerous words and quotes that continue to shape public understanding of political scandals. There’s “hush money” and “Deep Throat,” a “modified limited hangout” and “follow the money.” But half-a-century later, two other Watergate phrases are key to comprehending the FBI’s sordid role in suppressing The Post’s initial coverage of Hunter Biden’s laptop. The first is, “What did the president know and when did he know it?” In a 1973 Watergate hearing, the question about the president’s knowledge was asked by Sen. Howard Baker to White House counsel John Dean….