By Jonathan Saul LONDON (Reuters) – Western ship insurers are terminating cover for Russia’s leading shipping company Sovcomflot as multiple sanctions start to bite, companies involved say, adding to the growing challenges for the state-owned company and Moscow’s efforts to export oil and gas. Russia’s maritime sector is seeing the wind down of multiple services, including ship certification by leading foreign providers – vital for accessing ports and securing insurance – shipping companies pulling out and ship engine makers suspending training on their equipment after Moscow’s invasion of Ukr…