* Leaders, former leaders and diplomats meet Trump * Saudi Arabia's crown prince called him, source says * Worried about tariffs, Germany met Republican governors * Mexican candidate to tailor envoy choice if Trump wins, sources * Rudd pushed Canberra to Trump-proof submarine deal (Adds comment from South Korea's foreign ministry in paragraph 56) By Alexander Ratz, Diego Oré and Gram Slattery BERLIN/MEXICO CITY/WASHINGTON, April 24 (Reuters) - G ermany is waging a charm offensive inside the Republican Party. Japan is lining up its own Trump whisperer. Mexican government officials are talking to Camp Trump. And Australia is busy making...