UK leader Rishi Sunak fought to quell growing dissent within his ruling party Tuesday over his plan to send migrants to Rwanda, testing his authority with a general election on the horizon. Two deputy chairmen of the Conservatives resigned their roles as they joined dozens of Tory right-wingers in backing amendments to toughen the scheme, seen as key to Sunak’s pledge to cut immigration. The Conservative prime minister has staked his political future on slashing record levels of regular migration and stopping asylum seekers crossing from France to Britain in small boats. The Safety of Rwanda (…