(Reuters) - WeWork has started a search for a new chief executive following the departure of its co-founder Adam Neumann, people familiar with the matter said on Monday, as the U.S. office-sharing start-up seeks to reverse its widening losses. WeWork's current co-CEOs, Artie Minson and Sebastian Gunningham, have only been in place since September but the talks indicated SoftBank Group , WeWork's majority owner, is eager for a fresh change after a botched effort to go public this year. WeWork has..