President-elect Donald Trump exploded at media bigs in an off-the-record Trump Tower powow on Monday, sources told The Post. “It was like a f—ing firing squad,” said one source. “Trump started with Jeff Zucker and said I hate your network, everyone at CNN is a liar and you should be ashamed…. “The meeting was a total disaster. The TV execs and anchors went in there thinking they would be discussing the access they would get to the Trump administration, but instead they got a Trump-style dressing down,” the source added. A second source confirmed the encounter. “The meeting took place...