When longtime friends and associates of President Donald Trump want to reach him, they don’t go directly to the White House. Instead, they call the woman who’s been the gatekeeper at Trump Tower for a quarter century: Rhona Graff. Since Trump took office in January, Graff has become a conduit for those who want to quietly offer advice, make personnel suggestions or get on the president’s calendar when he’s at his Mar-a-Lago resort in Florida.