Crystal structure of the EGFR kinase domain (L858R, T790M, V948R) in complex with a covalent inhibitor N-[(3R,4R)-4-fluoro-1-{6-[(3-methoxy-1-methyl-1H-pyrazol-4-yl)amino]-9-(propan-2-yl)-9H-purin-2-yl}pyrrolidin-3-yl]propanamide