* Singapore-headquartered Grab to set up second HQ in Indonesia. : JAKARTA/SINGAPORE (Reuters) - Southeast Asian ride-hailing firm Grab on Monday said it will invest $2 billion into Indonesia over five years using capital from Japan’s SoftBank Group Corp, marking its biggest commitment in the region’s most populous market. The investment will go toward creating a next-generation transportation network and transforming how critical services, like healthcare, are delivered, Grab said in a statement. The push is likely to intensify rivalry with Indonesia’s Go-Jek.