[(R)‐2,2′‐Bis(diphenyl­phosphino)‐1,1′‐binaphthyl‐κ2P,P′]chloro­hydrido{(S)‐2‐methyl‐1‐[(4R,5R)‐4‐methyl‐5‐phenyl‐4,5‐dihydro­oxazol‐2‐yl]propan‐1‐amine‐κ2N,N′}ruthenium(II) benzene solvate: an active ketone hydrogenation catalyst