ROME — Italy’s interior minister and vice premier, Matteo Salvini, went off the grid for 12 hours during an official state visit to Moscow last October. Tales of Russian prostitutes seemed to explain the time lapse for the single statesman. But a new exposé by the Italian newsmagazine L’Espresso suggests that his time may have been spent doing something far more sinister: he may have been making backroom deals with Russian operatives ahead of European Parliamentary elections.