DETROIT — The Rocket is almost ready for liftoff. The 156-player field for the PGA Tour’s fourth annual Rocket Mortgage Classic was finalized Friday night, with the exception of five additional qualifiers to be settled Sunday and Monday. Among the notable withdrawals from the tournament was Justin Rose, ranked No. 50 in the world, though that wasn’t a big surprise to Rocket officials. Rose withdrew from the British Open two weeks ago with a balky back. More of a surprise was the pullout of world No. 38 Seamus Power and No. 97 Anirban Lahiri. Also decommitting from the Rocket were Lanto Griffin…