By Jeff Mason WASHINGTON (Reuters) -A man whose son was killed in the 2018 school shooting in Parkland, Florida, interrupted President Joe Biden’s remarks at the White House on Monday during an event to herald the passage of the first major federal gun safety law in three decades. Manuel Oliver, whose son Joaquin was murdered in the Marjory Stoneman Douglas High School massacre, shouted “we’ve already gone through this for years and years” at the event, during which Biden lauded the new law but said more needed to be done. “Sit down and you’ll hear what I have to say,” Biden said from the lect…