As U.S.-China relations remain tense, Southeast Asia becomes the darling for investors and tech companies from both sides as they seek overseas expansion. Behemoths like Google, Facebook, Alibaba, Tencent and ByteDance have elbowed into the region. Some set up shop, while others formed alliances and took stakes in local startups. Now five prominent investors originating from the region are ready to claim their slice of the market. Singapore-based Altara Ventures debuted this week with a goal to raise more than $100 million for its first fund focused on early-stage tech…