NEW YORK/SAN FRANCISCO (Reuters) - Growing tensions with North Korea should worry global electronics firms such as Apple Inc (NASDAQ:AAPL) as they source key parts from South Korea, but investors are brushing off such concerns and snapping up shares in key exporters, heartened by robust earnings and big investment plans.U.S. President Donald Trump said on Thursday in an interview with Reuters that a major conflict with North Korea is possible in the standoff over its nuclear and missile progra…