LONDON — Catherine, Princess of Wales, has been greeted with an outpouring of support and sympathy after she revealed Friday she had been diagnosed with cancer and was in the early stages of chemotherapy treatment.King Charles III said in a statement he was “so proud of Catherine for her courage in speaking as she did,” and that he had “remained in the closest contact with his beloved daughter-in-law throughout the past weeks.”Last month, Charles postponed public duties as Buckingham Palace revealed he had been diagnosed with cancer. Neither Charles, 75, nor Catherine, 42, have…