By Uditha Jayasinghe and Alasdair Pal COLOMBO/WEERAKETIYA, Sri Lanka (Reuters) – Sri Lankan President Gotabaya Rajapaksa said on Wednesday he would appoint a new prime minister and cabinet this week, after his elder brother and former premier Mahinda Rajapaksa resigned following deadly violence in the country. The new prime minister and cabinet will command a majority in the 225-seat parliament, Rajapaksa said, adding he will bring constitutional reforms to grant more power to the parliament. “I am taking steps to form a new government to control the current situation, to prevent the country f…