By Kate Abnett BRUSSELS (Reuters) -The European Union could introduce a gas price cap this winter to limit excessive price spikes, but only if countries give Brussels a mandate to propose the measure, the bloc’s energy chief said on Wednesday. After months of high gas prices driven by Russia slashing supplies, the 27-country EU is considering whether to cap prices – although with countries still split over the idea after weeks of talks, Brussels has not yet made a formal proposal to make it happen. The European Commission said last week it could make a legal proposal for a temporary “dynamic” …