By Charlie Conchie Gareth Southgate and the boss of Aviva will be among the headline speakers at the government’s global investment summit next week as Keir Starmer looks to flaunt the country in front of international financiers. In a programme outlining the schedule, sent to attendees this evening, the government said sessions would cover the new government’s “vision for the UK and mission to grow the economy” and the UK’s plans to reap “a stability dividend” under the new administration. The schedule, seen by City AM, reveals that the former England manager Gareth Southgate will appear on a…