Microsoft Corp. and G42, the United Arab Emirates’ top artificial intelligence firm, are joining forces to build a $1 billion geothermal-powered data center in Kenya, the initial phase of a multiyear plan to dramatically increase cloud-computing capacity in East Africa.G42 will lead the initial investment and handle the facility’s construction in Olkaria, which has abundant geothermal resources — a key benefit in a continent plagued by power outages and a potential boon for Microsoft’s efforts t...