LONDON — British Prime Minister Boris Johnson has picked Edward Lister, one of his key aides, to serve as his new special envoy for the Gulf and special projects. “The Gulf is a pivotal region both economically and geopolitically. I’m very pleased to be sending Lord Udny-Lister to work with our partners there and to unlock its potential,” Johnson said in a press statement. “His appointment marks my ambition to achieve a whole-scale modernization of our Gulf relationships, creating jobs and driving prosperity at home while delivering on our priorities and values overseas.” Lister, who will take up his appointment on Feb. 22, will report to the prime minister and work closely with the foreign secretary, secretary of state for international trade and the national security adviser.